A Case Study in Coordination Programming: Performance Evaluation of S-Net vs Intel's Concurrent Collections

We present a programming methodology and runtime performance case study comparing the declarative data flow coordination language S-Net with Intel's Concurrent Collections (CnC). As a coordination language S-Net achieves a near-complete separation of concerns between sequential software components implemented in a separate algorithmic language and their parallel orchestration in an asynchronous data flow streaming network. We investigate the merits of S-Net and CnC with the help of a relevant and non-trivial linear algebra problem: tiled Cholesky decomposition. We describe two alternative S-Net implementations of tiled Cholesky factorization and compare them with two CnC implementations, one with explicit performance tuning and one without, that have previously been used to illustrate Intel CnC. Our experiments on a 48-core machine demonstrate that S-Net manages to outperform CnC on this problem.Comment: 9 pages, 8 figures, 1 table, accepted for PLC 2014 worksho

Did farmers’ livelihood improve? An impact assessment of incorporating forages into the crop-livestock system in the coastal savannah zone of Ghana

The study used programming methods to assess the farm-level impact of incorporating forages, including dual purpose Cajanus cajan (C. cajan), into the crop-livestock system in the Coastal Savannah Zone of Ghana. The system was modeled in GAMS and solved using linear programming. The optimal enterprise mixes and their resultant net revenues with and without the interventions and therefore the change in net revenue were obtained. The intervention was to grow forages as part of the crop-livestock system and feed them to milking cows and their calves for increased milk production and growth. The grain of the forage was used as food by the farmers, and manure from the animals was also used for crop production. The effect of policy options like educating farmers to accept and use C. cajan grain as food and thereby increase its production was analysed. The change in net revenue with incorporation of C. cajan into the system was 50 percent. A 5 percentage points change in the inclusion level of C. cajan grain in farmers’ diet and subsequent increase in its cultivation precipitated a 4 percent change in net revenue. C. cajan was not produced beyond the level required for household consumption and its main attraction seemed to be its food value. The addition of C. cajan into the crop-livestock system of the area improved farmers’ incomes. Increased cultivation of C. cajan may be dependent on the food value of the crop for the household.GAMS, Ghana, Grain, Forages, Agricultural and Food Policy, Consumer/Household Economics, Crop Production/Industries, Farm Management, Food Consumption/Nutrition/Food Safety, Food Security and Poverty, Institutional and Behavioral Economics, International Relations/Trade, Livestock Production/Industries, Marketing, Productivity Analysis, Research and Development/Tech Change/Emerging Technologies,

Reconciling Economic and Biological Modeling of Migratory Fish Stocks:Optimal Management of the Atlantic Salmon Fishery in the Baltic Sea

The paper puts forward a model of the Atlantic salmon fishery in the Baltic Sea that integrates the salient biological and economic characteristics of migratory fish stocks. Designed to be compatible with the framework used for actual stock assessments, the model accounts for agestructured population dynamics, the seasonal harvest and competing harvesting by commercial and recreational fishermen. It is calibrated using data and parameter estimates for the Simojoki River stock. The socially optimal policy for maximizing discounted net benefits from the fishery within an uncertain environment is determined using a dynamic programming approach and numerical solution method. Our results indicate that substantial economic benefits could be realized under optimal management without compromising stock sustainability.Resource /Energy Economics and Policy,

An economic and environmental evaluation of the cost of conservation compliance on a Beaver Creek Watershed representative farm

Soil and water conservation continue to be important environmental concerns. Soil conservation and USDA program benefits became linked for the first time in history with passage of the Food Security Act of 1985. Conservation Compliance denies all USDA benefits to any person who produces an agricultural commodity on highly erodible land without the use of conservation practices appropriate for that land. The Conservation Compliance provisions of the Food Security Act of 1985 were enacted, in part, to reduce soil erosion and improve water quality. This study examined the impact of Conservation Compliance on a representative Beaver Creek Watershed farm. The study addressed the impacts on net return and soil erosion. Alternative Conservation Systems and stricter soil erosion constraints were evaluated. One specific objective of the study was to develop a linear programming model to evaluate the effects of alternative crop systems. Another objective was to evaluate the trade-offs, if any, between soil erosion control and net return. A linear programming model and a simulation model were integrated in this analysis. The Erosion Productivity-Impact Calculator was used to develop soil loss coefficients. The net return effect of compliance under the Alternative Conservation Systems was compared to the current practices. Further restrictions on soil erosion were also evaluated. Partial budgeting was used to develop coefficients for the farm. Net returns was compared with and without constraints on soil erosion. The implementation of Alternative Conservation Systems would reduce erosion on the representative farm by approximately 9,151 tons and net returns by $916 from the current farm practices. If soil erosion were constrained to less than 5-tons per acre, the erosion level would decrease by approximately 12,264 ton, and net returns by$25,247 from the current practices. Alternative Conservation Systems allow farm operators to reduce erosion substantially, but at the same time be cost effective for a given situation

Multi-Objective Programming for the Allocation of Trans-Boundary Water Resources - the Case of the Euphrates and Tigris

The allocation of water in a multi-country river system necessarily involves conflicting objectives, where increasing water benefits to one country may entail losses to other countries. This paper presents the formulation and application of a multi-objective linear programming model, where each objective represents the benefits to a country from using water for agricultural, municipal, and energy uses, net of conveyance costs. This model extends the Euphrates and Tigris River Basin Model (ETRBM), presented in Kucukmehmetoglu and Guldmann (2004), with the three objective functions representing the net water benefits to the three riparian countries – Turkey, Syria, and Iraq. The model is used to delineate the set of non-inferior solutions (Pareto frontiers), where no individual country benefit can be increased without reducing the benefits of at least another country. These Pareto frontiers, and the underlying water resources allocations, are graphically displayed and analyzed under different scenarios related to river flow, electricity price, and agricultural productivity. The trade-offs between the three benefits are assessed, providing the basis for possible compromises among the three countries. Potential policy implications for trans-boundary water resources utilization are discussed.

SafeWeb: A Middleware for Securing Ruby-Based Web Applications

Web applications in many domains such as healthcare and finance must process sensitive data, while complying with legal policies regarding the release of different classes of data to different parties. Currently, software bugs may lead to irreversible disclosure of confidential data in multi-tier web applications. An open challenge is how developers can guarantee these web applications only ever release sensitive data to authorised users without costly, recurring security audits. Our solution is to provide a trusted middleware that acts as a “safety net” to event-based enterprise web applications by preventing harmful data disclosure before it happens. We describe the design and implementation of SafeWeb, a Ruby-based middleware that associates data with security labels and transparently tracks their propagation at different granularities across a multi-tier web architecture with storage and complex event processing. For efficiency, maintainability and ease-of-use, SafeWeb exploits the dynamic features of the Ruby programming language to achieve label propagation and data flow enforcement. We evaluate SafeWeb by reporting our experience of implementing a web-based cancer treatment application and deploying it as part of the UK National Health Service (NHS)

Event-Driven Optimal Feedback Control for Multi-Antenna Beamforming

Transmit beamforming is a simple multi-antenna technique for increasing throughput and the transmission range of a wireless communication system. The required feedback of channel state information (CSI) can potentially result in excessive overhead especially for high mobility or many antennas. This work concerns efficient feedback for transmit beamforming and establishes a new approach of controlling feedback for maximizing net throughput, defined as throughput minus average feedback cost. The feedback controller using a stationary policy turns CSI feedback on/off according to the system state that comprises the channel state and transmit beamformer. Assuming channel isotropy and Markovity, the controller's state reduces to two scalars. This allows the optimal control policy to be efficiently computed using dynamic programming. Consider the perfect feedback channel free of error, where each feedback instant pays a fixed price. The corresponding optimal feedback control policy is proved to be of the threshold type. This result holds regardless of whether the controller's state space is discretized or continuous. Under the threshold-type policy, feedback is performed whenever a state variable indicating the accuracy of transmit CSI is below a threshold, which varies with channel power. The practical finite-rate feedback channel is also considered. The optimal policy for quantized feedback is proved to be also of the threshold type. The effect of CSI quantization is shown to be equivalent to an increment on the feedback price. Moreover, the increment is upper bounded by the expected logarithm of one minus the quantization error. Finally, simulation shows that feedback control increases net throughput of the conventional periodic feedback by up to 0.5 bit/s/Hz without requiring additional bandwidth or antennas.Comment: 29 pages; submitted for publicatio

What Makes Mountain Pine Beetle a Tricky Pest? Difficult Decisions when Facing Beetle Attack in a Mixed Species Forest

The pine forest of British Columbia is undergoing its largest recorded pest epidemic. The damage caused by native mountain pine beetle creates difficulties for the public owner of the resource, which is interested in protecting future timber supply while salvaging dead and dying pine. This paper addresses two problems that have often been over-looked: the variability and timing of beetle attack, and the variability of pine inventory in each stand. Management controls are limited to the annual rate of harvest and timber product outputs are based on shelf life – the length of time infested timber can still be used to produce lumber. Using mathematical programming to schedule harvest, we introduce a novel objective function based on the maximization of the net returns of the timber portfolio at the end of the 20 year time horizon under harvest and product flow constraints implemented by the public landowner to insure stability in the forest sector, and especially a stable supply of feedstock (bushchips) for bio-energy production, while recovering value from stands that would otherwise become uneconomical to harvest. The optimal short-run response is to increase harvests over the baseline harvest without beetle. The use of future net returns as the optimization objective ensures that harvest during the 20 year time horizon occurs in stands that would otherwise be economically unharvestable and also the harvest is generally above 70% pine in aggregate. Net returns do not exceed those of the baseline harvest without beetle, regardless of the scenario, as the harvest of low value bushchips must be subsidized by the harvest of timber that can be converted into lumber. Shelflife provides significant changes in NPV as more timber can be converted to lumber if shelflife is longer. The government has a difficult fiscal management problem. Employing an evenflow of total harvest can yield higher net gains but at the risk of relying more heavily on the harvest of damaged timber and reduced future harvests of quality timber for dimensional lumber. This strategy would produce a “feast” of short term revenue followed by a “famine” when bushchip harvest is subsidized by the harvest of better quality timber. Alternatively, managing the individual forest products could yield some minimum government revenues but this strategy could also lead to the need to deplete reserves that could be reserved for future timber supply. Regardless of the strategy, to optimize for future timber supply potential means that a large percentage (25% in this study) of the damaged pine should only be harvested in the future and will not be of a quality to produce lumber

Investigation of Electric Vehicles Contributions in an Optimized Peer-to-Peer Energy Trading System

The rapid increase in integration of Electric Vehicles (EVs) and Renewable Energy Sources (RESs) at the consumption level poses many challenges for network operators. Recently, Peer-to-Peer (P2P) energy trading has been considered as an effective approach for managing RESs, EVs, and providing market solutions. This paper investigates the effect of EVs and shiftable loads on P2P energy trading with enhanced Vehicle to Home (V2H) mode, and proposes an optimized Energy Management Systems aimed to reduce the net energy exchange with the grid. Mixed-integer linear programming (MILP) is used to find optimal energy scheduling for smart houses in a community. Results show that the V2H mode reduces the overall energy costs of each prosumer by up to 23% compared to operating without V2H mode (i.e., EVs act as a load only). It also reduces the overall energy costs of the community by 15% compared to the houses operating without the V2H mode. Moreover, it reduces the absolute net energy exchanged between the community and the grid by 3%, which enhances the energy independence of the community

.NET and C++ Interoperation

Käesolev töö kirjeldab, kuidas realiseerida koostöö kahe erineva programmeerimiskeskkonna, .NET-raamistiku ja programmeerimiskeele C++ vahel. .NET-raamistikku kasutades on arendaja produktiivsus suurem, kuid C++-is kirjutatud programmidel on parem jõudlus.\n\rSeega on eesmärk kasutada tarkvara arendamisel .NET-keeli (nt. C#), kuid jõudlus-kriitilistes kohtades kutsuda välja C++-koodi. Selleks tuleb luua vahekiht kasutades tehnoloogiaid Platform Invoke või C++/CLI.\n\rTöös kirjeldatakse vahekihi ülesehitust, selle loomise etappe ning tutvustatakse projekti, mis loob vahekihi automaatselt. Vahekihi automaatne loomine aitab vähendab töökulu ja parandada veakindlust. Lisaks analüüsitakse viise, kuidas korraldada mäluhaldust ja parandada jõudlust.C# is a modern programming language aimed at code robustness and development productivity, but it cannot compete with C++ in performance. The best of both worlds can be had by interoperating between the two languages.\n\rHowever, C# as a .NET language follows a different paradigm than C++ in many ways. For example, .NET cleans up memory using automatic garbage collection while C++ requires memory to be freed explicitly. Low-level memory access is natural in C++, but is strictly controlled in .NET. Not to mention differences in naming conventions and semantics.\n\rThis paper describes two approaches to creating an intermediate layer between .NET and C++ (Platform Invoke and C++/CLI) by making a wrapper interface around C++ code, explains how to overcome memory management and performance issues and introduces a framework for automatically generating the interface.\n\rBy combining .NET and C++, developers can build their application in a safe and productive manner without sacrificing speed in performance-critical parts of the code