Critical Parameter Research Papers - Academia.edu (original) (raw)

While research and development of algal biofuels are currently receiving much interest and funding, they are still not commercially viable at today's fossil fuel prices. However, a niche opportunity may exist where algae are grown as a by-product of high rate algal ponds (HRAPs) operated for wastewater treatment. In addition to significantly better economics, algal biofuel production from wastewater treatment HRAPs has a much smaller environmental footprint compared to commercial algal production HRAPs which consume freshwater and fertilisers. In this paper the critical parameters that limit algal cultivation, production and harvest are reviewed and practical options that may enhance the net harvestable algal production from wastewater treatment HRAPs including CO 2 addition, species control, control of grazers and parasites and bioflocculation are discussed.

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- Carbon Dioxide, Biomass, Water Purification, Wastewater Treatment

This work reports the validation of a simple CZE method to be used in quality control of recombinant human glycosylated interleukin-7 (rhIL-7) batches produced in Chinese Hamster Ovary (CHO) cells. The separation buffer was a 25mM sodium borate at pH 10 containing 12mM diaminobutane (DAB) used as a dynamic coating agent of the capillary. This method allowed the separation of seven peaks ranging from low to high sialylated glycoforms. An extensive study on conditioning methods of the capillary has been conducted to yield repeatable results. Excellent RSD of EOF mobility (less than 0.6%) was obtained when conditioning included capillary equilibration under virtual analyses and storage in 0.1M NaOH overnight. Method specificity has been demonstrated to be able to discriminate different rhIL-7 glycoforms produced in CHO from formulation matrix. Linearity was demonstrated between 0.5 and 4mg/mL. LOQ was 0.5mg/mL. Repeatability (RSD<1.4 and 3.3% for t(m) and A%, respectively), intermed...

- by Yousef Alahmad
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- Chemistry, Analytical Chemistry, Capillary electrophoresis, Comparative Study

There has been a rapid increase in the number and demand for approved biopharmaceuticals produced from animal cell culture processes over the last few years. In part, this has been due to the efficacy of several hu-manized monoclonal... more

- by H. Butler
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- Production, Biotechnology, Process Control, Apoptosis

The specific heat capacity of tissue is a critical parameter for thermal therapies that act over a long period of time. It is also critical for thermoacoustic signal generation. We present ex vivo measurements of specific heat capacity performed by a dual-pin probe with tight temperature control of the specimen. One 30 mm × 1.28 mm probe heats steadily for 30 s, while another measurement probe measures temperatures 6 mm away from the center of the heater probe. Specific heat values ranging from 2.9 to 4 J cm −3 • C −1 were measured on 20 lobes from ten fresh prostate specimens with varying degrees of cancerous involvement as confirmed by histology.

- by Nagesh B
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- Biomedical Engineering, Computer Simulation, Temperature, Prostate

The present paper aims to investigate the role of creative practices for settlements, with a special focus on the'Associations of the Most Beautiful Villages' in France and Italy. The paper focuses on the critical parameters of a locality related to the attractiveness of villages from the perspective of visitors and the role of the above-mentioned Associations from the perspective of the local population. Data and information used are derived from in-depth questionnaires filled out by relevant experts from 32 villages. In order to achieve this aim, ...

In silico (on the computer) oncology is a multi-disciplinary field that focuses on the examination and modeling of biological mechanisms related to the phenomenon of cancer. In silico oncology simulation model may be used for evaluating and comparing different therapeutic schemes while at the same time considering different values of critical parameters which present substantial inter-patient variability. As the number of the involved parameters and of the considered radiotherapeutic schemes increases, the resulting exponential increase in computational requirements makes the use of a grid environment for the execution of the simulations both a necessity for the involved researchers and an opportunity to make in silico oncology applications available to a wider biomedical and research community. In this paper, we describe a toolkit that enables the execution of in silico oncology simulations on grid infrastructures. This toolkit is designed and developed as a web portal with advanced features that facilitates the execution of in silico oncology simulations in grid environments. Several scenarios of radiotherapy simulations have been performed on the EGEE grid and indicative simulation results, as well as execution times are presented.

- by Dimitra Kaklamani
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- Grid Computing, Design and Development, Web Portal, In Silico

The winding hot-spot temperature is one of the most critical parameters that affect the useful life of the power transformers. The winding hot-spot temperature can be calculated as function of the top-oil temperature that can estimated by using the ambient temperature and transformer loading measured data. This paper proposes the estimation of the top-oil temperature by using a method based on Least Squares Support Vector Machines approach. The estimated top-oil temperature is compared with measured data of a power transformer in operation. The results are also compared with methods based on the IEEE Standard C57.91-1995/2000 and Artificial Neural Networks. It is shown that the Least Squares Support Vector Machines approach presents better performance than the methods based in the IEEE Standard C57.91-1995/2000 and artificial neural networks.

- by P. de Resende
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- Computer Science, Support Vector Machines, Modeling and Simulation, Transformer

Through a multi-disciplinary approach, the air amplifier is being evolved as a highly engineered device to improve detection limits of biomolecules when using electrospray ionization. Several key aspects have driven the modifications to the device through experimentation and simulations. We have developed a computer simulation that accurately portrays actual conditions and the results from these simulations are corroborated by the

- by Amarnatha Sarma Potturi
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- Chemistry, Analytical Chemistry, Organic Chemistry, Mass Spectrometry

The paper assesses the market conditions and dynamics, the architectures and the different approaches for deployment of 3G Mobile Virtual Network Operators (MVNOs), in an attempt to address specific advantages and pitfalls. Following the definition of appropriate service sets and tariff structures, and taking into account demand scenarios, a techno-economic model has been developed, in order to compute key economic indicators. The paper presents techno-economic results of specific business cases and deployment alternatives for an average "large" European country and a smaller, Nordic-type country. Fixed and variable costs have been identified and the business case shows how different service sets lead to different costs. Different MVNO business profiles have been investigated. Profitability for all scenarios and business profiles has been calculated, presented and discussed. Major opportunities and threats, as well as critical parameters and uncertainties have been identified through sensitivity analysis.

This paper focuses on the implementation of various diagnostics for optimizing chemical oxygen iodine laser. This paper also dwells on the measurement methodologies and instrumentation employed in these diagnostic systems. The prime diagnostics are for the measurement of vital species in form of iodine, singlet oxygen, and chlorine. Iodine concentration measurement (absorption at λ = 499 nm), chlorine utilization (absorption at λ = 330 nm), and singlet oxygen yield (emission at λ = 1.27 µm) have been implemented based on optical absorption/emission principle. Furthermore, online Mach number determination, which is critical for supersonic gas flows, laser pulse detection (at λ = 1315 nm), and flow rate measurement and control over wide range, have been carried out. A dedicated diagnostics and data acquisition system (DDAS) customized for parameter monitoring have been developed. The developed DDAS also serves the purpose of precise operation sequencing and parameter control. It is a 168-channel personal-computer-based system with customized interface electronics employing Visual C++ programming language with user-friendly graphical user interfaces. A detailed uncertainty analysis of various critical parameters has been also presented.

- by gaurav singhal
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- Programming Languages, Convergence, Instrumentation, Iodine

Dendritic cells (DCs) exposed to tumor antigens followed by treatment with T h 1-polarizing differentiation signals have paved the way for the development of DC-based cancer vaccines. Critical parameters for assessment of the optimal functional state of DCs and prediction of the vaccine potency of activated DCs have in the past been based on measurements of differentiation surface markers like HLA-DR, CD80, CD83, CD86, and CCR7 and the level of secreted cytokines like interleukin-12p70. However, the level of these markers does not provide a complete picture of the DC phenotype and may be insufficient for prediction of clinical outcome for DC-based therapy. We therefore looked for additional biomarkers by investigating the differential expression of microRNAs (miRNAs) in mature DCs relative to immature DCs. A microarray-based screening revealed that 12 miRNAs were differentially expressed in the two DC phenotypes. Of these, four miRNAs, hsa-miR-155, hsa-miR-146a, hsa-miR-125a-5p, and hsa-miR-29a, were validated by real-time polymerase chain reaction and northern blotting. The matured DCs from 12 individual donors were divided into two groups of highly and less differentiated DCs, respectively. A pronounced difference at the level of miRNA induction between these two groups was observed, suggesting that quantitative evaluation of selected miRNAs potentially can predict the immunogenicity of DC vaccines. ᭧

- by Mogens Claesson
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- Immunology, MicroRNA, Flow Cytometry, Dendritic Cells

The fatigue damage analysis is examined from a historical perspective. The analysis indicates that some of the issues concerning the basic disparities between the experiment and model/interpretations. To help understand these issues, we have developed an approach with two driving force parameters to analyze the fatigue behavior. Such an approach helps in viewing the damage in terms of an intrinsic problem rather than an extrinsic one. In the final analysis one needs to unify the overall damage processes such that the description is complete from the crack initiation stage to short crack to long crack to final failure. In order to unify the damage process, three basic parameters are introduced for describing the overall fatigue process. These are ⌬K, K max and internal stress contribution to K max. In addition, there are other effects from environment and temperature that can contribute to these parameters. In particular K max seems to play an important role in the overall damage process. We find that the internal stress is the missing link that can bridge the gap between the four main stages of damage that lies between the crack nucleation stage to final failure. Examples are sited in support of this view of explanation. Finally, it is suggested that systematic experimental data and analytical modeling to describe the internal stress gradients is required to help in forming a reliable life prediction methodology. Published by Elsevier Science Ltd.

- by A.K., Vasudevan and +1
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- Mechanical Engineering, Civil Engineering, Titanium, Fatigue

In this study, we compare three desalination based alternatives for water supply in off-grid areas, and assess their environmental footprint. The three options are: (a) a solar still, (b) a photo-voltaic (PV) powered reverse osmosis (RO) unit, and (c) water delivery by truck from a central RO plant. By use of life-cycle analysis (LCA), a comprehensive environmental modeling of the three systems is carried out. The basic systems, components and processes are modeled, and then varied, in order to offer a deeper insight into the robustness of the model.Our findings indicate that energy generation and materials usage are critical parameters when the considered alternative options are compared. Of the three options, PV-RO is found to have the least environmental impact. The usefulness of this study is that it provides policy-makers insights into renewable energy desalination for clean water production and, thus, it promotes the deployment of low-carbon desalination technologies.► Three desalination-based alternatives were assessed for environmental footprint. ► The life-cycle analysis (LCA) approach was used. ► A comprehensive environmental modeling of the three systems is carried out. ► Main finding: PV-RO has the least environmental impact.

- by Prasad Mande
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- Engineering, Renewable Energy, Environmental modeling, United Arab Emirates

This study empirically estimates some critical parameters of the aggregate import demand function for Bangladesh for Bangladesh using quarterly time series data and by applying the Johansen-Juselius multivariate cointegration technique. Cointegration results indicate that the import demand function is dominated by income and relative prices. The income elasticity is significantly positive and exceeds unity indicating that aggregate imports are to be considered as 'luxury' goods. The effect of the relative price variable is significantly negative but its elasticity coefficient is less than unity.

- by Anisul Islam
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- Econometrics, Macroeconomics, Applied Economics, Applied Economics Letters

Rapid, reliable and objective estimations of leaf area index (LAI) are essential for numerous studies of atmosphere-vegetation interaction, as LAI is very often a critical parameter in process-based models of vegetation canopy response to global environmental change. This paper reviews current knowledge concerning the use of direct and indirect methods for LAI determination. The value of optical LAI measurements by means of hemispherical photography has already been demonstrated in previous studies. As clumping seems to be the main factor causing errors in indirect LAI estimation, we suggest that the use of a digital camera with high dynamic range has the potential to overcome a number of described technical problems related to indirect LAI estimation. Further testing and defining of a standardised field protocol for digital hemispherical photography is however needed to improve this technique to achieve the standards of an ideal device.

- by Marie Weiss and +2
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- Earth Sciences, Global Environmental Change, Biological Sciences, High Dynamic Range

Cu and In ®lms have been deposited by direct current (d.c.) magnetron sputtering on glass substrates under different deposition conditions. Deposition temperature, partial pressure in the vacuum chamber, and thickness have been found to be the most critical parameters for achieving low resistivity ®lms. Resistivity of In ®lms was found to be more sensitive to deposition parameters than for Cu ®lms. For the deposition parameters studied in this work, changes in the resistivity of Cu ®lms are of the order of 10 1 , compared to In ®lm resistivity changes of order of 10 1 to 10 11 .

- by Julius Mwabora
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- Materials Engineering, Magnetron Sputtering, Critical Parameter, Direct Current

In this paper we compare two alternative theoretical approaches for simulating the growth of cell aggregates in vitro: individual cell (agent)-based models and continuum models. We show by a quantitative analysis of both a biophysical agent-based and a continuum mechanical model that for densely packed aggregates the expansion of the cell population is dominated by cell proliferation controlled by mechanical stress. The biophysical agent-based model introduced earlier (Drasdo and Hoehme in Phys Biol 2:133-147, 2005) approximates each cell as an isotropic, homogeneous, elastic, spherical object parameterised by measurable biophysical and cell-biological quantities and has been shown by comparison to experimental findings to explain the growth patterns of dense monolayers and multicellular spheroids. Both models exhibit the same growth kinetics, with initial exponential growth of the population size and aggregate diameter followed by linear growth of the diameter and power-law growth of the cell population size. Very sparse monolayers can be explained by a very small or absent cell-cell adhesion and large random cell migration. In this case the expansion speed is not controlled by mechanical stress but by random cell migration and can be modelled by the Fisher-Kolmogorov-Petrovskii-Piskounov (FKPP) reaction-diffusion equation. The growth kinetics differs from that of densely packed aggregates in that the initial spread, as quantified by the radius of gyration, is

- by Dirk Drasdo
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- Mathematical Biology, Agent Based, Cell Migration, Cell Adhesion

The origins of macrovoid and the ways to eliminate it have received great attention and heavy debates during the last five decades, but no convincing and agreeable comprehension has been achieved. We have discovered, for the first time, that there should be critical values of polymer concentration, air gap distance and take-up speed, only above all of which the macrovoid-free hollow fibers can be successfully produced from a two-component (one-polymer and one-solvent) system. This observation has been confirmed for hollow fibers spun from different materials such as polysulfone, P84 and cellulose acetate, and may be universally applicable for other polymers. The major mechanisms why these critical parameters can effectively suppress macrovoids have been elaborated. The concept of acceleration of stretch was proposed and a quantitative relationship was observed to relate it with the number of macrovoids per unit area at the critical velocity and critical air gap distance.

- by Na Peng
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- Engineering, Membrane Science, Concentration, CHEMICAL SCIENCES

Crop salt tolerance is generally assessed as the relative yield response to increasing root zone salinity, expressed as soil (EC e ) or irrigation water (EC w ) electrical conductivity. Alternatively, the dynamic process of salt accumulation into the shoot relative to the shoot biomass has also been considered as a tolerance index. These relationships are graphically represented by two intersecting linear regions, which identify (1) a specific threshold tolerance, at which yield begins to decrease, and (2) a declining region, which defines the yield reduction rate. Although the salinity threshold is intuitively a critical parameter for establishing plant salt tolerance, we focused our interest on physiological modifications that may occur in the plant at salinity higher than the so-called tolerance threshold. For this purpose, we exposed hydroponically grown tomato plants to eight different salinity levels (EC = 2.5 (non-salinized control); 4.2; 6.0; 7.8; 9.6; 11.4; 13.2; 15.0 dS m −1 ). Based on biomass production, water relations, leaf ions accumulation, leaf and root abscisic acid and stomatal conductance measurements, we were able to identify a specific EC value (approximately 9.6 dS m −1 ) at which a sharp increase of the shoot and root ABA levels coincided with (1) a decreased sensitivity of stomatal response to ABA; (2) a different partitioning of Na + ions between young and mature leaves; (3) a remarkable increase of the root-to-shoot ratio. The specificity and functional significance of this response in salt stress adaptation is discussed.

- by Giampaolo Raimondi
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- Stress, Salt Stress, Biological Sciences, Environmental Sciences

Hybrid plasma catalyst technology has great potential for indoor air purification. However, humidity is a critical parameter in plasma catalytic processes. In this work, several catalysts were tested downstream of a DC corona discharge and the effect of humidity was investigated on both ozone and toluene removal. Next, sorption measurements onto the catalysts were performed for toluene, trichloroethylene and acetone, using an equilibrium partitioning in closed system procedure to explain the obtained results in a quantitative manner.

- by jim van durme
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- Environmental Engineering, Chemical Engineering, Technology, Catalysis

The aim of this work was the study of the influence of the raw material composition on biodiesel quality, using a transesterification reaction. Thus, ten refined vegetable oils were transesterificated using potassium methoxide as catalyst and standard reaction conditions (reaction time, 1 h; weight of catalyst, 1 wt.% of initial oil weight; molar ratio methanol/oil, 6/1; reaction temperature, 60°C). Biodiesel quality was tested according to the standard . Automotive fuels. Fatty acid methyl esters (FAME) for diesel engines. Requirements and test methods]. Some critical parameters like oxidation stability, cetane number, iodine value and cold filter plugging point were correlated with the methyl ester composition of each biodiesel, according to two parameters: degree of unsaturation and long chain saturated factor. Finally, a triangular graph based on the composition in monounsaturated, polyunsaturated and saturated methyl esters was built in order to predict the critical parameters of European standard for whatever biodiesel, known its composition.

- by Maria Jose Ramos
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- Multidisciplinary, Fatty acids, Raw materials, Reaction Time

This paper presents design considerations to be taken in designing of a low temperature differential double-acting Stirling engine for solar application. The target power source will be a thermosiphon solar water heater with integrated storage system, which will supply a constant source temperature of 70° C. Hence, the system design is based on a temperature difference of 50° C, assuming that the sink is kept at 20° C. During the preliminary design stage, the critical parameters of the engine design are determined according to the ...

- by shahrir abdullah
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- Mechanical Engineering, Renewable Energy, Engineering Design, Heat Exchanger

A real-time system for protecting and monitoring a DC/AC converter has been designed and constructed. The proposed system consists of (a) a hardware protection unit for fast reaction, load protection and inverter fail-safe operation and (b) a microcontroller unit for calculating critical parameters of the inverter operation. The control unit malfunctions have not been investigated in this study. The proposed hardware architecture and sensors form a low-cost and reliable control unit. The experimental results show that the proposed system ensures the inverter protection and fail-safe features. The proposed unit can be used to increase the reliability of any power inverter in AC motor drives, renewable energy systems, etc. or can be incorporated in any UPS system.

- by Eyjólfur Reynisson
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- Biology, Food Processing, Food Technology and Biotechnology, Stainless Steel

Dynamic charge acceptance and charge acceptance under constant voltage charging conditions are for two reasons essential for lead-acid battery operation: energy efficiency in applications with limited charging time (e.g. PV systems or regenerative braking in vehicles) and avoidance of accelerated ageing due to sulphation. Laboratory tests often use charge regimes which are beneficial for the battery life, but which differ significantly from the operating conditions in the field.

- by Oliver Bohlen and +1
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- Engineering, Performance, Power, Lead Acid Batteries

Tape stripping is a simple and efficient method for the assessment of quality and efficacy of cosmetical and dermatological formulations. After topical application and penetration of formulations, the cell layers of the stratum corneum are successively removed from the same skin area using adhesive films. The tape strips contain the amount of corneocytes and the corresponding amount of the penetrated formulation, which can be determined by classical analytical chemical methods. Different formulations can strongly influence the amount of stratum corneum removed with every tape strip. Therefore, it is essential for the comparison of the penetration of different formulations that the amount of formulation detected on the single tape strip is not related to the tape strip number as a relative measure of the penetration depths, but to their standardized real position in the stratum corneum. Therefore, different methods are reported for the determination of the amount of stratum corneum removed with every tape strip.

- by Christian Surber
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- Skin, Cosmetics, Penetration Depth, Stratum Corneum

A shelf-life model based on the storage temperature was developed for a homogenized fruit-based baby food. Bottles of apple compote for infant feeding were collected from a food company and stored at three different temperatures (23, 30 and 37 C) during 420 days. CIELAB color space parameters, vitamin C, 5-hydroxymethylfurfural were measured and sensory analysis (sensory attributes and overall acceptability) was carried out during the length of the study. Weibull Hazard Method was utilized to set the shelf-life end-point of the product at 37 C according to overall acceptability score given by the sensory panel. Considering a 50% probability of panellists to find the product as being unacceptable, the end of shelf-life for the apple-based beikost stored at 37 C was achieved after 346 days. The statistical analysis of the data enabled us to select the most adequate zero-and first-order kinetic equations for both physicochemical and sensory attributes in samples stored at 37 C. Color CIELAB parameters, vitamin C and sensory attributes (color and taste) were selected as the critical parameters. Their rejection times at 23 and 30 C storage temperatures were obtained by extrapolation of the results given by Weibull method at 37 C. Finally, rejection times for critical parameters were used to propose a shelf-life equation that showed 4.5 and 3.4 years of shelf-life when stored at 20 and 23 C, respectively.

- by Fernando Romero
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- Statistical Analysis, Animal Production, SHELF LIFE, vitamin C

Spray pyrolysis has been applied to deposit a wide variety of thin films. These films were used in various devices such as solar cells, sensors, and solid oxide fuel cells. It is observed that often the properties of deposited thin films depend on the preparation conditions. An extensive review of the effects of spray parameters on film quality is given to demonstrate the importance of the process of optimization. The substrate surface temperature is the most critical parameter as it influences film roughness, cracking, crystallinity, etc. Processes involved in the spray pyrolysis technique are discussed in this review as well.

- by Ludwig J Gauckler
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- Materials Engineering, Solar Cell, Thin Films, Electroceramics

A mathematical model of biomass gasification in bubbling fluidized gasifier has been developed. It is a one-dimensional, two-phase (bubble and emulsion), two-zone (bottom dense bed and upper freeboard), steady state model. The model is based on global reaction kinetic, mass and energy balances and is capable of predicting temperature, solid hold ups and gas concentration along the reactor's major axis. The overall model has sub-models to deal with biomass pyrolysis, gasification, bed hydrodynamics, material classification and property calculation. A sub-model for tar generation and cracking is included in this study. The model is capable of dealing with wide variety of biomasses and fluidizing agents, i.e. air, oxygen, steam or a mix of these gases. Results show that during devolatilization step, gases release and mixing are sensitive and critical parameters. They have a strong influence on the overall performance of a gasifier. A comparison with experimental data from numerous literature works was done, which showed fairly good agreement. The model can be used to study and optimize the operation of bubbling fluidized bed gasifier. However, further validation with diverse data will help to fine-tune the model.

- by Nader Mahinpey
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- Mechanical Engineering, Chemical Engineering, Kinetics, Biomass

... transmitting and/or receiving side of the communication link, whose signals are processed adaptively in order to exploit the spatial dimension of the mobile radio channel. ... Angeliki Alexiou, Bell Laboratories, Lucent Technologies... more

- by Martin Haardt
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- Distributed Computing, Smart Antenna, Service Quality, Wireless Systems

While no simple electrical descriptor provides a good measure of defibrillation efficacy, the waveform parameters that most directly influence defibrillation are voltage and duration. Voltage is a critical parameter for defibrillation because its spatial derivative defines the electrical field that interacts with the heart. Similarly, waveform duration is a critical parameter because the shock interacts with the heart for the duration of the waveform. Shock energy is the most often cited metric of shock strength and an ICD’s capacity to defibrillate, but it is not a direct measure of shock effectiveness. Despite the physiological complexities of defibrillation, a simple approach in which the heart is modeled as passive resistor–capacitor (RC) network has proved useful for predicting efficient defibrillation waveforms. The model makes two assumptions: (1) The goal of both a monophasic shock and the first phase of a biphasic shock is to maximize the voltage change in the membrane at the end of the shock for a given stored energy. (2) The goal of the second phase of a biphasic shock is to discharge the membrane back to the zero potential, removing the charge deposited by the first phase. This model predicts that the optimal waveform rises in an exponential upward curve, but such an ascending waveform is difficult to generate efficiently. ICDs use electronically efficient capacitive-discharge waveforms, which require truncation for effective defibrillation. Even with optimal truncation, capacitive-discharge waveforms require more voltage and energy to achieve the same membrane voltage than do square waves and ascending waveforms. In ICDs, the value of the shock output capacitance is a key intermediary in establishing the relationship between stored energy—the key determinant of ICD size—and waveform voltage as a function of time, the key determinant of defibrillation efficacy. The RC model predicts that, for capacitive-discharge waveforms, stored energy is minimized when the ICD’s system time constant τ s equals the cell membrane time constant τ m, where τ s is the product of the output capacitance and the resistance of the defibrillation pathway. Since the goal of phase two is to reverse the membrane charging effect of phase one, there is no advantage to additional waveform phases. The voltages and capacitances used in commercial ICDs vary widely, resulting in substantial disparities in waveform parameters. The development of present biphasic waveforms in the 1990s resulted in marked improvements in defibrillation efficacy. It is unlikely that substantial improvement in defibrillation efficacy will be achieved without radical changes in waveform design.

This paper presents the modeling and characterization of an optical fiber grating for maximum reflectivity. Grating length and change in refractive index are the critical parameters in contributing to the performance of fiber Bragg grating. The wavelength chosen for analysis is from the third window to minimize the attenuation. The reflection spectra, bandwidth and side lobes strength were analyzed with different lengths and change in refractive index. The simulations are based on solving coupled mode equations by transfer matrix method that describes the interaction of guided modes.

- by Vivekanand Mishra
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- Simulation, Fiber Bragg grating, Refractive Index, Optical physics

The goal of this work is to present a general theoretical and practical framework of binder granulation that takes an agglomeration process from binder selection and testing to granule formation, growth and consolidation and finally to granule deformation and breakup. For agglomeration and granule growth to commence at all, a certain minimum amount of binder has to be introduced in the granulator and this has to be determined carefully. This paper presents special instrumentation and procedures tbr binder selection. In granulation processes such as detergents and pharmaceutical products, both the powders to be agglomerated and the binders are defined by the formulation and, usually, little liberty is given to alter the chemistry. Binder 'selection' in this case is practically reduced to adjusting the properties of the binder using small amounts of additives such as surfactams, polymeric compounds and small amounts of liquids and tailoring the binder to exhibit specific behavior. This allows fine-tuning of binder properties that include surface wetting, spreading, adsorption, binder strengthening and solid bridge strength. The bulk of the present work is dedicated to the theory of growth kinetics during granulation and the prediction of critical sizes which delimit different regimes of granulation. Several dimensionless parameters based on energy dissipation principles are presented and examples given about how these parameters and the critical sizes they define can be used to predict the outcome of granulation and the scale-up of the process. The above theoretical framework is then tested with experimental data from the literature and with granulation results obtained by the present authors using a specially constructed constant-shear granulator based on the principles of a Couette viscometer. A theory of consolidation of formed granules is also given and additional experimental support from the literature is presented. © 1997 Elsevier Science S.A.

- by Paul Mort
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- Mechanical Engineering, Chemical Engineering, Powder technology, Growth Kinetics

Insect pests persist in a wide-variety of agricultural, arboreal and urban environments. Effective control with fungal entomopathogens using inundation biocontrol requires an understanding of the ecology of the target insect, fungal pathogen, and the insect-pathogen interaction. Historically, the development of production and formulation processes for biocontrol fungi has primarily focused on reducing costs by maximizing the yield of infective propagules, increasing storage stability, and improving product form for ease of application. These goals are critical for commercialization but are often in conflict with environmental and ecological considerations. Critical parameters for selecting a fungal pathogen for use in inundation biocontrol include the cost-effective production of a stable, infective propagule that is suited for use in the environment where the insect must be controlled. Production processes can be manipulated nutritionally and environmentally to produce efficacious propagules or to direct fungal differentiation to propagule forms that may be better suited for use in specific environments. Formulation development must also consider ecological and environmental factors to maximize biocontrol efficacy. A basic understanding of the surface chemistries of the fungal propagule and insect, the interactions between a fungal propagule and the insect cuticle that lead to infection, and the impact of the environment on this interaction can aid in the development of effective formulations.

- by Stefan Jaronski
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- Surface Chemistry, Biological Sciences, Biocontrol, Cost effectiveness

Flapping-wing aerodynamics recently has generated a great deal of interest and increasing research effort because of the potential application in micro-air vehicles. The objective of this study is to critically review the recent progress of CFD analysis of flappingwing aerodynamics. Critical parameters like flapping modes, frequency and amplitude for optimal thrust generation and propulsive efficiency are identified. Current gaps in this research area with suggestions for further research are discussed. A preliminary CFD study to analyse the effects of the reduced frequency (k), amplitude of oscillation (h) and the maximum nondimensional flapping velocity (kh) on the thrust generation and efficiency of a NACA0012 airfoil undergoing pure plunge motion at a Reynolds number of 20,000 is performed and the insight gained is discussed. The results of the present study agree well with available experimental and computational data found in the literature, however at k = 2, h = 24 very high values of average thrust coefficient (C Tmean = 102) with very low propulsive efficiency (η P = 0.0006) are predicted.

- by Ashraf Ashraf
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- Numerical Analysis, Oscillations, Micro Air Vehicle, Reynolds Number

- by Priyanka Kaushal
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- Mechanical Engineering, Chemical Engineering, Kinetics, Fuel

Reliability is essential for electro-hydraulic systems due to the high energy densities associated with their operation. A failure can have catastrophic results, for example, if a contamination failure of hydraulic fluid at high pressure occurs. A novel approach for fault diagnosis of hydraulic systems has been proposed, using genetic algorithms as the parameter optimization method, and model based simulation. Performance tracking of critical parameters within the hydraulic system assesses subtle state changes and attempts to identify failure modes associated with these state changes. The proposed approach, which requires analysis of each component of the hydraulic system under normal operation and with specific, induced failure modes, has been successfully applied to a hydraulic system incorporating a servovalve and linear actuator. The results of this study provide a basis for future studies of more complex hydraulic components and systems.

- by Jacek Stecki
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- High Pressure, High Energy Density Physics, Genetic Algorithm, Performance Model

Solvent extraction technique is one of the cheapest and most efficient processes experienced in recycling of used lubricating oils. In this paper, the performance of three extracting solvents (2-propanol, 1-butanol, and methyl-ethyl-ketone (MEK) in recycling used oil was evaluated experimentally. The effect of the most critical parameters (type of solvent, solvent to oil ratio, and extraction temperature) was investigated. The results show that MEK achieved the best performance with the lowest percent oil losses, followed by 2-propanol and 1-butanol, and as the extraction temperature increases the percent oil losses decreases. The antisolvency energy (E s ), which originates from the solubility parameters difference between the solvent and oil was related to the solvent to oil ratio. It was found that the critical clarifying ratio predicted from such relations for the three solvents reasonably agrees with that measured experimentally. Relations between E s and solvent to oil ratio give a proper guideline for preliminary evaluation of the extracting solvent. It also can be used to predict the optimum solvent:oil ratio and extraction temperature based on the solvent ability to dissolve the base oil in used motor oil. # 2002 Published by Elsevier Science B.V. (S.M. Al-Zahrani). Chemical Engineering and Processing 41 (2002) 765 Á/769 www.elsevier.com/locate/cep 0255-2701/02/$ -see front matter # 2002 Published by Elsevier Science B.V. PII: S 0 2 5 5 -2 7 0 1 ( 0 2 ) 0 0 0 0 6 -5

A computational study using the discrete element method was performed to study the effect of pan speed, fill level and the design of the spray pattern on the coating variability of tablets coated in a rotating pan. The method simulates the movement of tablets in the pan and calculates the residence time of each tablet inside the spray zone, which is directly related to the amount of coating received by the tablet. The computational method was experimentally validated using a Laser Induced Breakdown Spectroscopy based analytical method. The simulations showed that the axial mixing was the most critical parameter affecting the coating variability. Although axial mixing was found to be better at higher pan speed, it did not affect the coating variability significantly. Lower variability was obtained when a 100% fill level was used as compared to 67% fill. Four spray patterns were used, two idealized (full surface spray and a symmetric band spray) and two realistic (5-ellipse and 5-circular spray guns). The full and band spray showed similar results while the ellipse and circular patterns were similar to each other (and much worse than the other two patterns) at all speeds and fill levels.

The paper summarizes the operating principles of a swahsplateless rotor; discusses the issues of modeling a swashplateless rotor helicopter by means of a comprehensive simulation model suitable for flight dynamics calculations; and presents the results of a numerical systematic investigation into the eects of swashplateless rotor design parameters such as trailing-edge flap length and span-wise position, pitch index, and blade

- by Carlos R Malpica
- •
- Indexation, Level, Critical Parameter, Simulation Model

Teknik sistemlerin verimliliği, güvenilirliği ve ekonomik ömrü gibi kritik parametreler bakım-onarım faaliyetlerinin etkinliği ile doğrudan ilişkilidir. Pratikte bu süreç; işletilen sistemin karakteristik özellikleri doğrultusunda, Toplam Üretken Bakım, Periyodik Bakım, Önleyici Bakım, Kestirimci Bakım, Arızi Bakım ve Güvenilirlik Merkezli Bakım gibi yaklaşımlarından uygun olanın seçilmesi ile oluşturulan bakım-onarım prosedürleri çerçevesinde yürütülmektedir. Ancak, teknolojik gelişmelerin katkısı nedeni ile artan sistem karmaşıklığı daha ileri bakım-onarım tekniklerinin uygulanmasını gerektirmektedir. Bu çalışmada, Bulanık Bilgi Aksiyomu yöntemi kullanılarak gemi makine dairesindeki farklı nitelikteki sistemler için karakteristik ve fonksiyonel özellikleri doğrultusunda entegre bakım-onarım yönetimi gereksinimi ortaya konulacaktır. Uygulanan karar modeli çıktıları kullanılarak, mevcut durumda planlı bakım sistemi uygulanan ticari gemiler için genişletilmiş ve daha etkin bir bakım-onarım yönetimi sistematiği oluşturulacaktır. ABSTRACT Effectiveness of maintenance management is directly related to critical parameters of technical systems such as efficiency, reliability, and economic life. In practice, this process is executed via procedures on selected adequate maintenance method among which the alternatives such as Total Productive Maintenance, Planned Maintenance, Preventive Maintenance, Predictive Maintenance, Reactive Maintenance, or Reliability Centered Maintenance. However, increasing system complexity due to the contributions of technological developments requires implementing more advance maintenance planning techniques. In this study, an integrated maintenance management system is presented based on Fuzzy Information Axioms methodology for shipboard systems under various characteristics and functional attributes. An extended and more effective maintenance management systematic is developed for merchant ships using applied decision model outcomes.

Tortuosity and cementation factor are two critical parameters that significantly affect estimates of reservoir properties. Tortuosity factor can be used to estimate permeability using the Carman-Kozeny equation and is an important parameter for formation resistivity factor calculation using a modified version of Archie's formula. It is also used to predict water saturation of reservoir rocks. Tortuosity as an input parameter in Biot's equation can be used to estimate velocity dispersion.

- by Abdolrahim Javaherian
- •
- Porosity, Permeability, Carbonate Rock, Curve fitting

This article presents a technical innovation, study of solar power system based on the Stirling dish (SD) technology and design considerations to be taken in designing of a mean temperature differential Stirling engine for solar application. The target power source will be solar dish/Stirling with average concentration ratio, which will supply a constant source temperature of 320 1C. Hence, the system design is based on a temperature difference of 300 1C, assuming that the sink is kept at 20 1C. During the preliminary design stage, the critical parameters of the engine design are determined according to the dynamic model with losses energy and pressure drop in heat exchangers was used during the design optimisation stage in order to establish a complete analytical model for the engine. The heat exchangers are designed to be of high effectiveness and low pressure-drop. Upon optimisation, for given value of difference temperature, operating frequency and dead volume there is a definite optimal value of swept volume at which the power is a maximum. The optimal swept volume of 75 cm 3 for operating frequency 75 Hz with the power is 250 W and the dead volume is of 370 cm 3 .

- by Iskander Tlili
- •
- Mechanical Engineering, Design, Renewable Energy, Engineering Design

Platinum group elements (PGE) and Au data in polymetallic oceanic ferromanganese nodule reference samples and crust samples obtained by inductively coupled plasma mass spectrometry (ICP-MS), after separation and pre-concentration by nickel sulfide fire-assay and Te coprecipitation, are presented. By optimizing several critical parameters such as flux composition, matrix matching calibration, etc., best experimental conditions were established to develop a method suitable for routine analysis of manganese nodule samples for PGE and Au. Calibrations were performed using international PGE reference materials, WMG-1 and WMS-1. This improved procedure offers extremely low detection limits in the range of 0.004 to 0.016 ng/g. The results obtained in this study for the reference materials compare well with previously published data wherever available. New PGE data are also provided on some international manganese nodule reference materials. The analytical methodology described here can be used for the routine analysis of manganese nodule and crust samples in marine geochemical studies. [Key words : Platinum group elements (PGE), gold, manganese nodule reference samples, manganese crust, NiS fire-assay, ICP-MS] [IPC code: Int. Cl. (2006) G01 N 31/02]

Guar gum produces films that lack in clarity and have poor tensile strength. Hence guar gum was modified chemically for improving its film forming properties. The derivatives were evaluated as film coating material by coating dummy tablets. To take the advantage of both solvent and aqueous coating processes and overcome their limitations, a combined coating formulation was developed comprising the major portion of solvent as water and minor portion of solvent as isopropanol. This combination of solvents improved the drying rate which is the most critical parameter in aqueous film coating. The coated tablets were studied for various tablet parameters such as hardness, friability loss, film adhesion and disintegration. Accelerated stability studies were carried out at 40 0 C and at 75 % relative humidity for period of 6 months.

- by Vinita Kale
- •
- Relative Humidity, Tensile Strength, Critical Parameter, Guar Gum

Dark fermentation CSTR Lactose Organic loading rate PCR-DGGE a b s t r a c t

- by Gustavo Davila-Vazquez
- •
- Engineering, Sequence Analysis, Hydrogen Energy, Polymerase Chain Reaction

The efficiency of a bank of dense medium cyclones treating medium coking coal in the size range of y13 q 0.5 mm was evaluated. Performance indicators for evaluating the efficiency of the separation were identified. Various variables affecting the efficiency of the dense medium Ž Ž Corelations were then developed relating the coefficient of separation showing the separation . efficiency and the E to the design and operating variables of the cyclones. q 2001 Elsevier p Science B.V. All rights reserved. . 0301-7516r01r$ -see front matter q 2001 Elsevier Science B.V. All rights reserved. Ž . PII: S 0 3 0 1 -7 5 1 6 0 1 0 0 0 4 8 -5 ( ) R. Sripriya et al.r Int.

- by sripriya R
- •
- Mechanical Engineering, Chemical Engineering, Mineral Processing, Mathematical Model

This paper studies different organophosphorus extractants for the selective recovery of metal ions such as Cu (II), Co (II), Ni (II), Pb (II), Fe (III), Cd (II) from effluents resulting from the metal finishing at the time of industry process. In a first step, a commercial extractant such as di(2ethylhexyl)phosphoric acid (D2EHPA) was used as carrier for SLM extraction. Combining D2EHPA and TOPO (tri-octylphosphine oxide) leads to enhanced extraction of Cu (II), Ni (II) and Co (II). The influence of other critical parameters such as pH, ionic strength and mass transfer resistance of the feed was investigated as well as the diffusion of metal ions and membrane permeation. D2EHPA showed good extraction efficiency for Pb (II) (91%) in the mixture, whereas it is lower for Cu (II) (9%). When TOPO was added to D2EHPA, the extraction efficiency of copper increases up to 57%. In a second step, new organophosphorus extractants, synthesized by microwave irradiation, were tested in SLM extraction of metal ions. Di[p-(1,1 ,3,3 -tetramethylbutyl)phenyl] phosphoric acid (DOPPA) and 1,12-(4,9-dioxatrisdecanyl)diphosphonic acid (DOTDDA), selectively extracted Cu (II) and Co (II) (100%) from Fe (III), Cd (II), Pb (II) and Ni (II) in the mixture (0%), whereas methylenediphosphonic acid (MDPA) is a good carrier for Cd (II) (83%), Pb (II) (69%) and Ni (II) (63%) extraction. However 1,13-diamino-4,7,10-trioxatridecanyltetramethylene phosphonic acid (DATOMPA) is useful for extraction of trace metals (Fe (III); 72%). For a selective extraction of Co (II) and Cu (II) from other metals, DOPPA shows the highest extraction efficiency for these two cations, whereas the rest of heavy metals tested are not extracted. (J.Å. Jönsson).

- by Didier Villemin
- •
- Engineering, Mass Transfer, Membrane Science, Trace Metals

Relative to conventional air drying, superheated steam (SHS) drying provides a number of benefits such as increased efficiency, reduced risk of fire and explosion, sterilization, deodorization and faster drying rates. Brewer's spent grain (BSG) is the by-product from beer brewing. It is a sticky material with a tendency to foul drying equipment. This paper evaluates the drying behaviour of BSG in a pilot-scale rotary SHS dryer. The evaluation is based on product moisture content, measurements of sticking and energy consumption.