alex zhang - Academia.edu (original) (raw)
Papers by alex zhang
Report and presentation completed by students enrolled in PA 8202: Networks and Places, taught by... more Report and presentation completed by students enrolled in PA 8202: Networks and Places, taught by Dr. Jason Cao in spring 2013.
Physics and Chemistry of Liquids, 2019
Experimental solubility data are reported for anthracene, biphenyl, benzil, benzoin, 1-chloroanth... more Experimental solubility data are reported for anthracene, biphenyl, benzil, benzoin, 1-chloroanthraquinone, phenothiazine, pyrene, salicylamide, thioxanthen-9-one, xanthene, benzoic acid, 4-tert-butylbenzoic acid, 4-chloro-3-nitrobenzoic acid, 3,4-dichlorobenzoic acid, 3,4-dimethoxybenzoic acid, 2-hydroxybenzoic acid, 4-methoxybenzoic acid, 2-methylbenzoic acid, 3-methylbenzoic acid, 3-methyl-4-nitrobenzoic acid, 4-nitrobenzoic acid and 3,4,5-trimethoxybenzoic acid dissolved in dimethyl carbonate at 298.15 K. Abraham model correlations are derived for solute transfer into dimethyl carbonate by combining our measured solubility data with published activity coefficient and solubility data retrieved from the published chemical and engineering literature. The derived Abraham model correlations back-calculate the 52 experimental molar solubilities and infinite dilution activity coefficients to within 0.13 log units.
Physics and Chemistry of Liquids, 2019
Spectroscopic methods have been used to determine the mole fraction solubilities of 4-methyl-3-ni... more Spectroscopic methods have been used to determine the mole fraction solubilities of 4-methyl-3-nitrobenzoic acid dissolved in 17 different alcohols (methanol, ethanol, 1-propanol, 1-butanol, 1-pentanol, 1-hexanol, 1-heptanol, 1-octanol, 1-decanol, 2-propanol, 2-butanol, 2-methyl-1-propanol, 2-pentanol, 2-methyl-1-butanol, 3-methyl-1-butanol, 4-methyl-2-pentanol, 2-ethyl-1-hexanol), two dialkyl ether (diethyl ether, diisopropyl ether) and two cyclic ether (tetrahydrofuran, 1,4-dioxane), four alkyl alkanoate (methyl acetate, ethyl acetate, butyl acetate, pentyl acetate) and one alkanenitrile (acetonitrile) solvents at 298.15 K. Results of experimental measurements are used to calculate the Abraham model solute descriptors of 4-methyl-3-nitrobenzoic acid. The calculated Abraham model solute descriptors describe the observed solubility behaviour of 4-methyl-3-nitrobenzoic acid to within 0.05 log units.
Journal of Solution Chemistry, 2018
Experimental infinite dilution activity coefficients, gas-to-liquid partition coefficients, and m... more Experimental infinite dilution activity coefficients, gas-to-liquid partition coefficients, and molar solubility data have been measured for numerous organic solutes dissolved in propyl acetate. Results of our experimental measurements, combined with published solubility data retrieved from the published literature, have been used to derive Abraham model correlations for describing solute transfer into propyl acetate. The derived Abraham model correlations describe the experimental data to within 0.11 log 10 units. Calculation of Abraham model solute descriptors for boscalid was illustrated using our derived solute transfer correlations into propyl acetate. Predictions using the calculated solute descriptors indicate that boscalid would show significant partitioning into the skin and fat tissues in the body, and would exhibit considerable baseline toxicity towards the eight aquatic organisms (five fish species and three water flea species). Keywords Infinite dilution activity coefficients Á Gas-to-organic solvent partition coefficients Á Water-to-organic solvent partition coefficients Á Molar solubilities Á Aquatic toxicity Á Blood-to-tissue partition coefficients & William E. Acree Jr.
2015 Sustainable Internet and ICT for Sustainability (SustainIT), 2015
For most businesses, backup is a daily operation that needs to reliably protect diverse digital a... more For most businesses, backup is a daily operation that needs to reliably protect diverse digital assets distributed across the enterprise. Efficiently processing ever increasing amounts of data residing on multiple desktops, servers, laptops, etc., and providing dynamic recovery capabilities becomes a high priority task for many IT departments. Driven by the advances in cloud computing and Software as a Service (SaaS) delivery model, IT departments are transitioning from providing highly customized services to offering on demand services which can be requested and canceled instantly. Backup service providers must be able to react efficiently to on-demand requests and cannot afford labor intensive resource planning and manual adjustments of schedules. Our goal is to automate the design of a backup schedule that minimizes the overall completion time for a given set of backup jobs. This problem can be formulated as a resource constrained scheduling problem where a set of jobs should be scheduled on machines with given capacities. In this work, we compare the outcome of the integer programming formulation with a heuristic-based job scheduling algorithm, called FlexLBF. The FlexLBF schedule produces close to optimal results (reducing backup time 20%-60%) while carrying no additional computing overhead and scaling well to efficiently process large datasets compared to the IP-based solution. Moreover, FlexLBF can be easily analyzed in a simulation environment to further tune a backup server configuration for achieving given performance objectives while saving power (up to additional 50% in our experiments). It helps to avoid guess-based configuration efforts by system administrators and significantly increase the quality and reliability of implemented solutions.
2010 International Conference on Network and Service Management, 2010
Many industries experience an explosion in digital content. This explosion of electronic document... more Many industries experience an explosion in digital content. This explosion of electronic documents, along with new regulations and document retention rules, sets new requirements for performance efficiency of traditional data protection and archival tools. During a backup session a predefined set of objects (client filesystems) should be backed up. Traditionally, no information on the expected duration and throughput requirements of different backup jobs is provided. This may lead to a suboptimal job schedule that results in the increased backup session time. In this work, we characterize each backup job via two metrics, called job duration and job throughput. These metrics are derived from collected historic information about backup jobs during previous backup sessions. Our goal is to automate the design of a backup schedule that minimizes the overall completion time for a given set of backup jobs. This problem can be formulated as a resource constrained scheduling problem where a set of n jobs should be scheduled on m machines with given capacities. We provide an integer programming (IP) formulation of this problem and use available IP-solvers for finding an optimized schedule, called binpacking schedule. Performance benefits of the new bin-packing schedule are evaluated via a broad variety of realistic experiments using backup processing data from six backup servers in HP Labs. The new bin-packing job schedule significantly optimizes the backup session time (20%-60% of backup time reduction). HP Data Protector (DP) is HP's enterprise backup offering and it can directly benefit from the designed technique. Moreover, significantly reduced backup session times guarantee an improved resource/power usage of the overall backup solution.
Physics and Chemistry of Liquids, 2014
Experimental solubilities have been determined for 1-chloroanthraquinone, anthracene, biphenyl, p... more Experimental solubilities have been determined for 1-chloroanthraquinone, anthracene, biphenyl, pyrene, benzil, benzoic acid, acetylsalicylic acid, 4-tert-butylbenzoic acid, 3,4-dichlorobenzoic acid, 2-chloro-5-nitrobenzoic acid, 4-chloro-3-nitrobenzoic acid, 2-methoxybenzoic acid, 4-methoxybenzoic acid, 3,4-dimethoxybenzoic acid, 3,4,5-trimethoxybenzoic acid, 2-methylbenzoic acid, 3-methylbenzoic acid, 4-methyl-3-nitrobenzoic acid, 4-nitrobenzoic acid, benzoin, salicylamide, thioxanthen-9-one, 1,4-dichloro-2-nitrobenzene and phenothiazine dissolved in diethyl carbonate at 298.15 K. Results of our experimental measurements, combined with published solubility and activity coefficient data, have been used to derive Abraham model correlations for describing solute transfer into diethyl carbonate. The derived mathematical correlations back-calculate the observed experimental data to within an overall standard deviation of 0.13 log units.
Nanomedicine: Nanotechnology, Biology and Medicine, 2012
Control over thrombin activity is much desired to regulate blood clotting in surgical and therape... more Control over thrombin activity is much desired to regulate blood clotting in surgical and therapeutic situations. Thrombin-binding RNA and DNA aptamers have been used to inhibit thrombin activity and thus the coagulation cascade. Soluble DNA aptamers, as well as two different aptamers tethered by a flexible single-strand linker, have been shown to possess anticoagulant activity. Here, we link multiple aptamers at programmed positions on DNA nanostructures to optimize spacing and orientation of the aptamers and thereby to maximize anticoagulant activity in functional assays. By judicious engineering of the DNA nanostructures, we have created a novel, functional DNA nanostructure, which is a multi-aptamer inhibitor with activity eightfold higher than free aptamer. Reversal of the thrombin inhibition was also achieved by the use of single-stranded DNA antidotes, thus enabling significant control over blood coagulation. From the Clinical Editor: Thrombin inhibition via DNA aptamers has recently become a possibility. In this study, thrombin-binding DNA aptamers were further optimized by nanoscale organization on DNA nanostructures. The authors have created a novel, functional DNA nanostructure, which is a multi-aptamer inhibitor with activity eightfold higher than that of free aptamer. Reversal of thrombin inhibition was also achieved by single-stranded DNA antidotes, enabling significant control over the coagulation pathway.
Infrared Physics & Technology, 2011
We report on the design and fabrication of (Al)GaAs(Sb)/InAs tensile strained quantum-dot (QD) ba... more We report on the design and fabrication of (Al)GaAs(Sb)/InAs tensile strained quantum-dot (QD) based detector material for thermal infrared imaging applications in the long-wavelength infrared (LWIR) regime. The detection is based on transitions between confined dot states and continuum states in a type-II band lineup, and we therefore refer to it as a dot-to-bulk (D2B) infrared photodetector with expected benefits
IIE Transactions, 1998
Page 1. The multiple lot sizing problem with rigid demand and interrupted geometric yield ALEX X.... more Page 1. The multiple lot sizing problem with rigid demand and interrupted geometric yield ALEX X. ZHANG1 and SY-MING GUU2 1Department of Information and Operations Management, School of Business Administration, University ...
IIE Transactions, 1999
Page 1. The newsboy problem with multiple demand classes ALPER SËEN and ALEX X. ZHANG Department ... more Page 1. The newsboy problem with multiple demand classes ALPER SËEN and ALEX X. ZHANG Department of Information and Operations Management, Marshall School of Business, University of Southern California, Los Angeles ...
European Journal of Operational Research, 2009
For many industries (e.g., apparel retailing) managing demand through price adjustments is often ... more For many industries (e.g., apparel retailing) managing demand through price adjustments is often the only tool left to companies once the replenishment decisions are made. A significant amount of uncertainty about the magnitude and price sensitivity of demand can be resolved using the early sales information. In this study, a Bayesian model is developed to summarize sales information and pricing history in an efficient way. This model is incorporated into a periodic pricing model to optimize revenues for a given stock of items over a finite horizon. A computational study is carried out in order to find out the circumstances under which learning is most beneficial. The model is extended to allow for replenishments within the season, in order to understand global sourcing decisions made by apparel retailers. Some of the findings are empirically validated using data from U.S. apparel industry.
European Journal of Operational Research, 2003
We consider the multiple lot sizing problem in production systems with random process yield losse... more We consider the multiple lot sizing problem in production systems with random process yield losses governed by the interrupted geometric (IG) distribution. Our model differs from those of previous researchers which focused on the IG yield in that we consider a finite number of setups and inventory holding costs. This model particularly arises in systems with large demand sizes. The
European Journal of Operational Research, 1998
... RESEARCH Joint demand fulfillment probability in a multiitem inventory system with independen... more ... RESEARCH Joint demand fulfillment probability in a multiitem inventory system with independent orderupto policies Warren H. Hausman a, Hau L. Lee a, Alex X. Zhang ... 2, b = 2. (b) zl* as a function of p; parameters: h1 = 0.5, h2 = 1.5, b = 2. sider the isoprobability curve Oz(zt, zz ...
HP Laboratories Technical Report HPL-2006-76, 2006
Distributed applications play an increasingly crucial role in business-critical enterprise operat... more Distributed applications play an increasingly crucial role in business-critical enterprise operations. Understanding the performance of such applications is challenging yet essential due to their growing economic value. A particularly important problem is performance ...
Report and presentation completed by students enrolled in PA 8202: Networks and Places, taught by... more Report and presentation completed by students enrolled in PA 8202: Networks and Places, taught by Dr. Jason Cao in spring 2013.
Physics and Chemistry of Liquids, 2019
Experimental solubility data are reported for anthracene, biphenyl, benzil, benzoin, 1-chloroanth... more Experimental solubility data are reported for anthracene, biphenyl, benzil, benzoin, 1-chloroanthraquinone, phenothiazine, pyrene, salicylamide, thioxanthen-9-one, xanthene, benzoic acid, 4-tert-butylbenzoic acid, 4-chloro-3-nitrobenzoic acid, 3,4-dichlorobenzoic acid, 3,4-dimethoxybenzoic acid, 2-hydroxybenzoic acid, 4-methoxybenzoic acid, 2-methylbenzoic acid, 3-methylbenzoic acid, 3-methyl-4-nitrobenzoic acid, 4-nitrobenzoic acid and 3,4,5-trimethoxybenzoic acid dissolved in dimethyl carbonate at 298.15 K. Abraham model correlations are derived for solute transfer into dimethyl carbonate by combining our measured solubility data with published activity coefficient and solubility data retrieved from the published chemical and engineering literature. The derived Abraham model correlations back-calculate the 52 experimental molar solubilities and infinite dilution activity coefficients to within 0.13 log units.
Physics and Chemistry of Liquids, 2019
Spectroscopic methods have been used to determine the mole fraction solubilities of 4-methyl-3-ni... more Spectroscopic methods have been used to determine the mole fraction solubilities of 4-methyl-3-nitrobenzoic acid dissolved in 17 different alcohols (methanol, ethanol, 1-propanol, 1-butanol, 1-pentanol, 1-hexanol, 1-heptanol, 1-octanol, 1-decanol, 2-propanol, 2-butanol, 2-methyl-1-propanol, 2-pentanol, 2-methyl-1-butanol, 3-methyl-1-butanol, 4-methyl-2-pentanol, 2-ethyl-1-hexanol), two dialkyl ether (diethyl ether, diisopropyl ether) and two cyclic ether (tetrahydrofuran, 1,4-dioxane), four alkyl alkanoate (methyl acetate, ethyl acetate, butyl acetate, pentyl acetate) and one alkanenitrile (acetonitrile) solvents at 298.15 K. Results of experimental measurements are used to calculate the Abraham model solute descriptors of 4-methyl-3-nitrobenzoic acid. The calculated Abraham model solute descriptors describe the observed solubility behaviour of 4-methyl-3-nitrobenzoic acid to within 0.05 log units.
Journal of Solution Chemistry, 2018
Experimental infinite dilution activity coefficients, gas-to-liquid partition coefficients, and m... more Experimental infinite dilution activity coefficients, gas-to-liquid partition coefficients, and molar solubility data have been measured for numerous organic solutes dissolved in propyl acetate. Results of our experimental measurements, combined with published solubility data retrieved from the published literature, have been used to derive Abraham model correlations for describing solute transfer into propyl acetate. The derived Abraham model correlations describe the experimental data to within 0.11 log 10 units. Calculation of Abraham model solute descriptors for boscalid was illustrated using our derived solute transfer correlations into propyl acetate. Predictions using the calculated solute descriptors indicate that boscalid would show significant partitioning into the skin and fat tissues in the body, and would exhibit considerable baseline toxicity towards the eight aquatic organisms (five fish species and three water flea species). Keywords Infinite dilution activity coefficients Á Gas-to-organic solvent partition coefficients Á Water-to-organic solvent partition coefficients Á Molar solubilities Á Aquatic toxicity Á Blood-to-tissue partition coefficients & William E. Acree Jr.
2015 Sustainable Internet and ICT for Sustainability (SustainIT), 2015
For most businesses, backup is a daily operation that needs to reliably protect diverse digital a... more For most businesses, backup is a daily operation that needs to reliably protect diverse digital assets distributed across the enterprise. Efficiently processing ever increasing amounts of data residing on multiple desktops, servers, laptops, etc., and providing dynamic recovery capabilities becomes a high priority task for many IT departments. Driven by the advances in cloud computing and Software as a Service (SaaS) delivery model, IT departments are transitioning from providing highly customized services to offering on demand services which can be requested and canceled instantly. Backup service providers must be able to react efficiently to on-demand requests and cannot afford labor intensive resource planning and manual adjustments of schedules. Our goal is to automate the design of a backup schedule that minimizes the overall completion time for a given set of backup jobs. This problem can be formulated as a resource constrained scheduling problem where a set of jobs should be scheduled on machines with given capacities. In this work, we compare the outcome of the integer programming formulation with a heuristic-based job scheduling algorithm, called FlexLBF. The FlexLBF schedule produces close to optimal results (reducing backup time 20%-60%) while carrying no additional computing overhead and scaling well to efficiently process large datasets compared to the IP-based solution. Moreover, FlexLBF can be easily analyzed in a simulation environment to further tune a backup server configuration for achieving given performance objectives while saving power (up to additional 50% in our experiments). It helps to avoid guess-based configuration efforts by system administrators and significantly increase the quality and reliability of implemented solutions.
2010 International Conference on Network and Service Management, 2010
Many industries experience an explosion in digital content. This explosion of electronic document... more Many industries experience an explosion in digital content. This explosion of electronic documents, along with new regulations and document retention rules, sets new requirements for performance efficiency of traditional data protection and archival tools. During a backup session a predefined set of objects (client filesystems) should be backed up. Traditionally, no information on the expected duration and throughput requirements of different backup jobs is provided. This may lead to a suboptimal job schedule that results in the increased backup session time. In this work, we characterize each backup job via two metrics, called job duration and job throughput. These metrics are derived from collected historic information about backup jobs during previous backup sessions. Our goal is to automate the design of a backup schedule that minimizes the overall completion time for a given set of backup jobs. This problem can be formulated as a resource constrained scheduling problem where a set of n jobs should be scheduled on m machines with given capacities. We provide an integer programming (IP) formulation of this problem and use available IP-solvers for finding an optimized schedule, called binpacking schedule. Performance benefits of the new bin-packing schedule are evaluated via a broad variety of realistic experiments using backup processing data from six backup servers in HP Labs. The new bin-packing job schedule significantly optimizes the backup session time (20%-60% of backup time reduction). HP Data Protector (DP) is HP's enterprise backup offering and it can directly benefit from the designed technique. Moreover, significantly reduced backup session times guarantee an improved resource/power usage of the overall backup solution.
Physics and Chemistry of Liquids, 2014
Experimental solubilities have been determined for 1-chloroanthraquinone, anthracene, biphenyl, p... more Experimental solubilities have been determined for 1-chloroanthraquinone, anthracene, biphenyl, pyrene, benzil, benzoic acid, acetylsalicylic acid, 4-tert-butylbenzoic acid, 3,4-dichlorobenzoic acid, 2-chloro-5-nitrobenzoic acid, 4-chloro-3-nitrobenzoic acid, 2-methoxybenzoic acid, 4-methoxybenzoic acid, 3,4-dimethoxybenzoic acid, 3,4,5-trimethoxybenzoic acid, 2-methylbenzoic acid, 3-methylbenzoic acid, 4-methyl-3-nitrobenzoic acid, 4-nitrobenzoic acid, benzoin, salicylamide, thioxanthen-9-one, 1,4-dichloro-2-nitrobenzene and phenothiazine dissolved in diethyl carbonate at 298.15 K. Results of our experimental measurements, combined with published solubility and activity coefficient data, have been used to derive Abraham model correlations for describing solute transfer into diethyl carbonate. The derived mathematical correlations back-calculate the observed experimental data to within an overall standard deviation of 0.13 log units.
Nanomedicine: Nanotechnology, Biology and Medicine, 2012
Control over thrombin activity is much desired to regulate blood clotting in surgical and therape... more Control over thrombin activity is much desired to regulate blood clotting in surgical and therapeutic situations. Thrombin-binding RNA and DNA aptamers have been used to inhibit thrombin activity and thus the coagulation cascade. Soluble DNA aptamers, as well as two different aptamers tethered by a flexible single-strand linker, have been shown to possess anticoagulant activity. Here, we link multiple aptamers at programmed positions on DNA nanostructures to optimize spacing and orientation of the aptamers and thereby to maximize anticoagulant activity in functional assays. By judicious engineering of the DNA nanostructures, we have created a novel, functional DNA nanostructure, which is a multi-aptamer inhibitor with activity eightfold higher than free aptamer. Reversal of the thrombin inhibition was also achieved by the use of single-stranded DNA antidotes, thus enabling significant control over blood coagulation. From the Clinical Editor: Thrombin inhibition via DNA aptamers has recently become a possibility. In this study, thrombin-binding DNA aptamers were further optimized by nanoscale organization on DNA nanostructures. The authors have created a novel, functional DNA nanostructure, which is a multi-aptamer inhibitor with activity eightfold higher than that of free aptamer. Reversal of thrombin inhibition was also achieved by single-stranded DNA antidotes, enabling significant control over the coagulation pathway.
Infrared Physics & Technology, 2011
We report on the design and fabrication of (Al)GaAs(Sb)/InAs tensile strained quantum-dot (QD) ba... more We report on the design and fabrication of (Al)GaAs(Sb)/InAs tensile strained quantum-dot (QD) based detector material for thermal infrared imaging applications in the long-wavelength infrared (LWIR) regime. The detection is based on transitions between confined dot states and continuum states in a type-II band lineup, and we therefore refer to it as a dot-to-bulk (D2B) infrared photodetector with expected benefits
IIE Transactions, 1998
Page 1. The multiple lot sizing problem with rigid demand and interrupted geometric yield ALEX X.... more Page 1. The multiple lot sizing problem with rigid demand and interrupted geometric yield ALEX X. ZHANG1 and SY-MING GUU2 1Department of Information and Operations Management, School of Business Administration, University ...
IIE Transactions, 1999
Page 1. The newsboy problem with multiple demand classes ALPER SËEN and ALEX X. ZHANG Department ... more Page 1. The newsboy problem with multiple demand classes ALPER SËEN and ALEX X. ZHANG Department of Information and Operations Management, Marshall School of Business, University of Southern California, Los Angeles ...
European Journal of Operational Research, 2009
For many industries (e.g., apparel retailing) managing demand through price adjustments is often ... more For many industries (e.g., apparel retailing) managing demand through price adjustments is often the only tool left to companies once the replenishment decisions are made. A significant amount of uncertainty about the magnitude and price sensitivity of demand can be resolved using the early sales information. In this study, a Bayesian model is developed to summarize sales information and pricing history in an efficient way. This model is incorporated into a periodic pricing model to optimize revenues for a given stock of items over a finite horizon. A computational study is carried out in order to find out the circumstances under which learning is most beneficial. The model is extended to allow for replenishments within the season, in order to understand global sourcing decisions made by apparel retailers. Some of the findings are empirically validated using data from U.S. apparel industry.
European Journal of Operational Research, 2003
We consider the multiple lot sizing problem in production systems with random process yield losse... more We consider the multiple lot sizing problem in production systems with random process yield losses governed by the interrupted geometric (IG) distribution. Our model differs from those of previous researchers which focused on the IG yield in that we consider a finite number of setups and inventory holding costs. This model particularly arises in systems with large demand sizes. The
European Journal of Operational Research, 1998
... RESEARCH Joint demand fulfillment probability in a multiitem inventory system with independen... more ... RESEARCH Joint demand fulfillment probability in a multiitem inventory system with independent orderupto policies Warren H. Hausman a, Hau L. Lee a, Alex X. Zhang ... 2, b = 2. (b) zl* as a function of p; parameters: h1 = 0.5, h2 = 1.5, b = 2. sider the isoprobability curve Oz(zt, zz ...
HP Laboratories Technical Report HPL-2006-76, 2006
Distributed applications play an increasingly crucial role in business-critical enterprise operat... more Distributed applications play an increasingly crucial role in business-critical enterprise operations. Understanding the performance of such applications is challenging yet essential due to their growing economic value. A particularly important problem is performance ...