Johnny Garcia - Academia.edu (original) (raw)

Papers by Johnny Garcia

A system that does not stand alone is represented by a complex entity of component combinations t... more A system that does not stand alone is represented by a complex entity of component combinations that interact with each other to execute a function. In today's interconnected world, systems integrate with other systems - called a system-of-systems infrastructure: a network of interrelated systems that can often exhibit both predictable and unpredictable behavior. The current state-of-the-art evaluation process of these system-of-systems and their community of practitioners in the academic community are limited to static methods focused on defining who is doing what and where. However, to answer the questions of why and how a system operates within complex systems-of-systems interrelationships, a system's architecture and context must be observed over time, its executable architecture, to discern effective predictable and unpredictable behavior. The objective of this research is to determine a method for evaluating a system's executable architecture and assess the contrib...

Mediation services can be generally defined as a mechanism to map interchange formats (map them t... more Mediation services can be generally defined as a mechanism to map interchange formats (map them to what?), thus increasing the ability for disparate systems to exchange information through common methods. However, when intelligent software agents use these meditation services, syntactical translations of formats are not sufficient. The semantic context has to be captured and interchanged as well; a common ontology is needed as the basis for the mediation service. While in the commercial world several recent publications are looking at possible automated solutions, in complex environments (is the commercial world not complex?), data engineering is necessary in order to support semantically meaningful mediation layers. Model-based data management uses a common reference model to map data models to data sources to support intelligent software agents for their internal decision processes This paper defines the phases of data engineering, shows potential conflicts and how they can be solved, and gives an example from the military application domain by showing how the Command and Control Information Exchange Data Model (C2IEDM) developed by the North Atlantic Treaty Organization (NATO) can be used as a common reference model for military applications.

The Journal of Defense Modeling and Simulation: Applications, Methodology, Technology, 2013

ABSTRACT Systems engineering (SE) addresses the six interrogatives who, what, where, when, why, a... more ABSTRACT Systems engineering (SE) addresses the six interrogatives who, what, where, when, why, and how. Architecture artifacts provide static descriptions addressing the first three interrogatives: who, what, and where. Executable architectures add the interrogative when, allowing for a dynamic evaluation of system performance. We propose an approach that takes the evaluation process further by addressing the final interrogatives why and how: embedding executable system architectures into an executable context (EC), creating a scenario in which to evaluate the system in the operational role and evaluate mission effectiveness. Combining existing contributions into an executable context simulation framework allows for a holistic evaluation of systems that are models based on engineering specifications in operationally relevant contexts. We have successfully implemented a prototype to demonstrate feasibility and usefulness of this recommended new approach.

Spring Simulation Multiconference, 2007

In order to better serve the testing and training community through modeling and simulation of jo... more In order to better serve the testing and training community through modeling and simulation of joint operation scenarios, Joint Operation Logistics Transformation and Training (JOLTT) offers a low threat but highly realistic capability for testing and analysis of joint warfighting. JOLTT offers users the ability to transform and preserve US joint tactical procedures along with advancing engineering to better support

Biological Control, 2006

Frosty pod rot (FPR), caused by Moniliophthora roreri, and black pod (BP), caused by Phytophthora... more Frosty pod rot (FPR), caused by Moniliophthora roreri, and black pod (BP), caused by Phytophthora spp., of cocoa (Theobroma cacao) cause combined pod losses of more than 80% in Panama. Biological control of both diseases appeared promising in Peru and is desired by certiWed organic producers in Panama. We evaluated both local and Peruvian fungal antagonists in participatory trials on smallholdings during two complete production cycles. Furthermore, we tested the inXuence of a 3% v/v cane molasses amendment on biocontrol eYcacy, yield and population dynamics of mycoparasites on the cocoa pod. SigniWcant variation was observed between the two years: FPR was more severe in the Wrst year, BP in the second. FPR was signiWcantly reduced by biocontrol agents (BCAs), but not by the molasses amendment. However, BCAs responded diVerently to molasses in both years. All BCAs reduced inoculum production by M. roreri with no consistent eVect of molasses. BCAs had a lesser and more variable eVect on BP, whereas molasses reduced BP slightly by increasing the eYcacy of native antagonists. All BCAs and the molasses amendment enhanced the percentage of healthy pods. Molasses was beneWcial to absolute yield, but only one inoculum improved yield signiWcantly in the Wrst year. Populations of a Peruvian Trichoderma asperellum isolate remained high for over two months after application to surface-sterilized pods. Molasses had no eVect on establishment or survival of this antagonist or recolonization by any native mycoparasite. The reasons for enhanced biocontrol eYcacy of the molasses formulation requires further investigation.

Biological Control, 2010

Frosty pod rot (FPR), caused by Moniliophthora roreri, reduces yields of cocoa (Theobroma cacao) ... more Frosty pod rot (FPR), caused by Moniliophthora roreri, reduces yields of cocoa (Theobroma cacao) by over 80% within a few years of disease outbreak. Both biological and chemical control approaches are being developed to supplement cultural management. Our objectives were to optimize the agent(s), their formulation and application regime for FPR control in Costa Rica. In order to economize scarce resources for field research, we opted for an iterative optimization of treatments. We aimed to (partly) replace copper hydroxide of proven efficacy with two systemic agents, the coevolved endophyte Trichoderma ovalisporum and the oxathiin flutolanil, and assessed four stickers for improving the agents' performance. Over 3 years, we selected effective agents and their combinations: eight of 18 treatments increased yields. Orthogonal contrasts extracted three general trends: (1) Copper should be applied in water, whereas the systemic agents were best formulated with a sticker. There was no difference between the stickers BreakThru and NP-7. (2) If the first rule was observed, a switch from systemic agent to the contact fungicide in mid season was beneficial. The optimum timing for this change requires further definition. (3) T. ovalisporum-containing agents controlled black pod better than flutolanil-based ones; both systemic agents were equally effective in controlling the more severe FPR. We discuss potential benefits of switching agents in the context of organic agriculture and argue that coevolved endophytes may be particularly suited for the classical biocontrol of Moniliophthora spp. in cocoa planted outside its South American centre of origin.

Annals of Applied Biology, 2005

This article describes two field trials carried out at La Lola, Costa Rica, to assess control mea... more This article describes two field trials carried out at La Lola, Costa Rica, to assess control measures against frosty pod rot of cocoa (Theobroma cacao) caused by Moniliophthora (Crinipellis) roreri. In the first, factorial, trial the control agents were applied using motorised mistblowers (MMs) and hydraulic sprayers fitted with a narrow angle cone nozzle. There was an interaction between agents and application methods; together with previous application data for the most active fungicide (copper hydroxide), these trials indicate that best yields are achieved with sprays that maximise deposits on pods. We describe the droplet size spectra produced by a Stihl SR400 MM under a range of conditions because this has become the standard method of fungicide application in this series of trials at La Lola. The factor that had the largest effect on droplet size spectrum was the presence or the absence of a detachable baffle plate in front of the air-shear nozzle. In both trials described here, MMs were fitted with baffle plates, a formulation pump and restrictor transmitting 550 mL min 21 to deliver an estimated equivalent of 190 L ha 21. Copper hydroxide as prophylactic applications at 1500 g a.i. ha 21 have, to date, shown the most consistent (but incomplete) improvement in healthy pod yield. Use of copper fungicides may be cost effective when farm-gate cocoa prices exceed approximately $1.25 kg 21. In these trials, isolates of the hyperparasitic fungi Clonostachys byssicola and Trichoderma asperellum and two offpatent triazole fungicides (bitertanol and triadimenol) made no significant improvement to healthy yields. The systemic oxathiin fungicide flutolanil, at a dosage of 300 g a.i. ha 21 , appears to protect pods substantially at early stages but gives proportionately less control of M. roreri than copper at later stages of pod development.