High-performance Configuration Research Articles

Public Capacity, Plural Forms of Collaboration, and the Performance of Public Initiatives: A Configurational Approach

AbstractWe assess conditions that explain plural forms of public and private action using a comparative study of 24 public initiatives in Brazil, India, and South Africa. Measuring performance as evidence of positive outcomes to their target populations, we compare cases of high and low performance. Our configurational approach examines combinations of conditions leading to positive outcomes: public operational capacity, diverse collaborations nurtured by public units (with for-profit firms, with nonprofit organizations, and with other units in the public bureaucracy), and stakeholder orientation (permeability to multiple sources of input to design and adjust the project). We apply fuzzy set qualitative comparative analysis to unveil configurations consistent with high performance. Our configurational analysis reveals two distinct paths to high performance. A path with higher private engagement involves concurrent collaborations with for-profit and nonprofit actors, whereas an alternative path with higher internal (public) engagement relies on collaborations within the public bureaucracy complemented by high permeability to inputs from multiple stakeholders. Our results also confirm that strong public capacity is necessary in all high-performance configurations. An important implication is that externalization and multiple forms of collaboration are not substitutes for weak governments. Furthermore, our configurational perspective contributes to the literature by operationalizing a multiple-actor, multiple-logic perspective describing alternative paths to high performance.

High Gain Antenna Miniaturization With Parasitic Lens

The scenario of using a spatially distributed antenna for miniaturized applications is presented in this work. A model of lens antenna with a low profile, compact, and high focusing superstrate, which exquisitely combines the conventional lens and resonant cavity superstrates, is proposed. Based on this model, the parasitic lens superstrate is introduced with high performance and simple configuration. The parasitic lens includes a low dielectric substrate and high resonant parasitic elements. By manipulating the surface currents of parasitic elements concentrating at center region of superstrate, the focusing effect is obtained. A prototype of the parasitic lens antenna was implemented with the source and parasitic superstrate’s lateral dimensions of $0.5\lambda _{0}\times 0.5\lambda _{0}$ and $\lambda _{0}\times \lambda _{0}$ , respectively, and the profile of $0.54\lambda _{0}$ . The peak gain is 10 dBi, corresponding to the enhancement of 5 dB. The measured results perspicuously demonstrate the efficiency of the compact parasitic lens.

Optimization of building form and its fenestration in response to microclimate conditions of an urban area

Designing building form in urban areas is a complicated process that demands considering a high number of influencing parameters. On the other hand, there has been an increasing trend to design highly fenestrated building envelopes for office buildings to induce higher levels of natural lighting into the workspace. This paper presents a novel optimization framework to design high-performance building form and fenestration configuration considering the impacts of urban microclimate in typical and extreme weather conditions during a thirty-year period of climate data (2010-2039). In this regard, based on the introduced technique and algorithm, the annual energy demand and thermal comfort of over 8008 eligible form combinations with eight different fenestration configurations and seven different building orientation angels were analysed in a detailed urban area to find optimal design solutions in response to microclimate conditions. Results showed that adopting the framework, annual heating, and cooling demand can be reduced by 21% and 38% while maintaining thermal comfort by taking design-based decisions at the early stages of design.

Performance Modeling and Directives Optimization for High-Level Synthesis on FPGA

High-level synthesis (HLS) relies on the use of synthesis directives to generate digital designs meeting a set of specifications. However, the selection of directives depends largely on designer experience and knowledge of the target architecture and digital design. Existing automated methods of directive selection are very limited in scope and capability to analyze complex design descriptions in high-level languages to be synthesized using HLS. This paper proposes a comprehensive model-based analysis (COMBA) framework which is capable of analyzing the effects of a multitude of directives related to functions, loops and arrays in the design description using pluggable analytical models, a recursive data collector and a metric-guided design space exploration (DSE) algorithm. COMBA reports a small average error in estimating performance when compared with HLS tools like Vivado HLS, and finds a high-performance configuration of synthesis directives within minutes. Given different resource constraints, COMBA finds configurations with higher speed-ups, compared with the state-of-the-art. Moreover, COMBA can guide the performance and area trade-off analysis. Experiments show that our DSE algorithm outperforms the conventional genetic algorithm, and COMBA efficiently finds a near-optimal configuration, which proves the efficiency of our tool for optimizing the practical HLS based designs.

Solar chimney power plants – Dimension matching for optimum performance

Solar chimney power plants are very large structures with the potential to generate significant amounts of electricity. Plant dimensions such as the collector diameter and chimney height and radius are important in determining system performance. The objective of this study is to identify the key parameters that drive performance. Performance was assessed in terms of power output and power output per cost. Using a detailed thermodynamic model, the plant power output was predicted for a wide range of design and operational parameters. It was found that the optimum pressure drop ratio depends on the collector and chimney radius, but not on chimney height, ambient temperature or insolation. The dimensions of the main components must be well matched to achieve best performance. Chimney radii of up to 200 m are essential to achieve maximum power generation up to 900 MW. Optimum power output exists for variation of the collector and chimney radius. However, increasing the chimney height always results in increased power generation. The physical phenomena underpinning high-performing configurations were highlighted. Power and efficiency increase with increased plant dimensions, but technological limits exist for the chimney height. A simple but robust cost model was introduced to identify optimum configurations in terms of power output per cost. Different relative costs between collector and chimney the optimum dimensions were selected. It was concluded that several smaller plants with collector radius about 3000 m are advantageous over one larger plant. Taller chimneys are economically beneficial until the specific chimney costs increase more than quadratically with height.

Entropy Generation and Heat Transfer Performance in Microchannel Cooling.

Owing to its relatively high heat transfer performance and simple configurations, liquid cooling remains the preferred choice for electronic cooling and other applications. In this cooling approach, channel design plays an important role in dictating the cooling performance of the heat sink. Most cooling channel studies evaluate the performance in view of the first thermodynamics aspect. This study is conducted to investigate flow behaviour and heat transfer performance of an incompressible fluid in a cooling channel with oblique fins with regards to first law and second law of thermodynamics. The effect of oblique fin angle and inlet Reynolds number are investigated. In addition, the performance of the cooling channels for different heat fluxes is evaluated. The results indicate that the oblique fin channel with 20° angle yields the highest figure of merit, especially at higher Re (250–1000). The entropy generation is found to be lowest for an oblique fin channel with 90° angle, which is about twice than that of a conventional parallel channel. Increasing Re decreases the entropy generation, while increasing heat flux increases the entropy generation.

Dynamic Balance Strategy of High Concurrent Web Cluster Based on Docker Container

With the rapid development of the Internet in today’s world, there are more and more applications based on network in our daily life, and the changes put forward higher requirements to the web systems of concurrency, scalability and availability. Based on the research of the Docker container virtualization technology and the container management platform Kubernetes, by improving the load balance strategies of Round-Robin and Weighted Round-Robin, this paper proposes a high-concurrency and easy-extending high concurrency cluster dynamic balance strategy to support the web system, which can guarantee the web system of high concurrency and high availability performance, implement reasonable and flexible configuration of system resources and realize the functions of automatic management and performance monitor of the system.

High piezoelectric performance and domain configurations of (K0.45Na0.55)0.98Li0.02Nb0.76Ta0.18Sb0.06O3 lead-free ceramics prepared by two-step sintering

Research for high-performance lead-free piezoelectric materials has become an urgent issue from the environmental concern. Very limited attempts on two-step sintering had been made so far. In this study, (K0.45Na0.55)0.98Li0.02Nb0.76Ta0.18Sb0.06O3 ceramics were prepared by both conventional sintering and two-step sintering. Piezoelectric properties, microstructure and domain structure were found to change significantly with sintering methods and sintering conditions. Two-step sintering was performed in the way that temperature is first quickly raised to 1180 °C, kept for 1 min, then immediately cooled down to 1120 °C and maintained for a desired time length. The effects of dwelling time on piezoelectric performance and microstructure as well as domain structure were investigated. High piezoelectric properties of d33 = 455 pC/N, kp = 0.54 and k33 = 0.67 were obtained in a ceramic prepared under the dwelling time of 20 h. This ceramic also possesses a very good piezoelectric thermal-ageing stability over −50 °C–150 °C. Further investigation reveals that this ceramic has a quite uniform grain-size distribution with the average grain size of about 12 μm in microstructure and shows domain patterns of simple parallel stripes with a hierarchical nanodomain structure appearing inside some of broad stripes. The observed excellent piezoelectric performance is considered to associate closely with the unique domain structure.

High Performance and Flexible Configuration Data Acquisition and Processing Unit in All Digital PET System

High Performance and Flexible Configuration Data Acquisition and Processing Unit in All Digital PET System

レベルセット法に基づく複数材料を対象としたトポロジー最適化

Topology optimization is the most flexible type of structural optimization method. This method has been applied in a variety of physics problems dealing with a multitude of design problems. In a given design problem, however, the optimization problem often has conflicting evaluative functions, such as the need for high rigidity in combination with minimal weight. The difficulty of simultaneously achieving high performance for two or more functions may be further compounded because current topology optimization methods typically only deal with a single material. On the other hand, when multiple kinds of materials having various properties can be selected for use, the range of a designer's choices is increased and an appropriate solution that greatly improves product functions may be achieved. Thus, this paper presents a new topology optimization method for multi-materials that obtains high-performance configurations. We apply the Multi-Material Level Set (MM-LS) topology description model in the topology optimization method, which uses a total of n level set functions to represent n materials, plus the void phase. The advantage of the MM-LS model is that clear optimal configurations are obtained and the design sensitivity for multi-material structures can be easily calculated. The level set functions that are design variables are updated using the topological derivatives, which also function as design sensitivities, and we derive the topological derivatives for multiple materials. Through several numerical examples, we demonstrate the validity of the proposed method.

A novel high performance configuration of electrochemical cell to produce alkali for sequestration of carbon dioxide

We propose a new configuration of a 3-compartment electrochemical cell for producing alkali that is subsequently utilized for mineralization of carbon dioxide. In this new membrane configuration, a second cation exchange membrane (CEM) replaces the anion exchange membrane (AEM) employed in a standard cell configuration. The electrochemical cell comprising of two cation exchange membranes (a CEM-CEM system) eliminates the issues associated with the AEM such as low ionic conductivity and inferior mechanical strength. All of tested CEM-CEM combinations exhibit superior electrochemical performance with considerable reduction of energy requirement for NaOH production in comparison to the standard AEM-CEM configuration. The optimized two-CEMs-based system presents a remarkable enhancement of output current density by 2.5-fold and a substantial input energy savings up to 740kWhton−1 for mineralization of carbon dioxide to produce sodium carbonate.

How important is customer orientation for firm performance? A fuzzy set analysis of orientations, strategies, and environments

Prior literature suggests that customer orientation interacts with other strategic factors, but yields mixed effects in terms of performance outcomes. In addition, capturing performance outcomes of complex systems of interdependencies using commonly employed methods, such as regression models, is often difficult. Thus, this study employs a configurational approach, using fuzzy set Qualitative Comparative Analysis (fs/QCA), to analyze the constellations of different strategic orientations, strategy types, and market conditions that yield superior performance. The study finds no evidence of high-performing configurations without customer orientation and shows that highly performing firms configure themselves around their customer orientation in three different ways. The results have implications for market orientation theory as well as for configurational and (marketing) strategy research in general.

Rapid motion planning algorithm for optimal UVMS interventions in semi-structured environments using GPUs

In this work, a novel local motion planning algorithm is presented, for underwater vehicle manipulator systems (UVMS) that perform autonomous underwater inspection operations. An optimization problem is formulated considering the collision avoidance, the approximation of the given task curve and critical optimization criteria. The searching method is based on an evolutionary algorithm and it is able to generate a local motion plan using continuously updated sensor information. The working environment is represented by a Bump-surface entity, constantly updated by a parallel algorithm implemented on a graphical processing unit (GPU). A trained artificial neural network is used for the fast approximation of the considered dexterity index. The local planner can cope with unknown obstacles inside the workspace while executing the task and pursuing high performance configurations in the free space. A welding inspection on an underwater tube structure is considered as the validation scenario, while a UVMS with a mounted six degrees of freedom manipulator is assigned to perform the task.

All-Electric Ship Energy System Design Using Classifier-Guided Sampling

The addition of power-intensive electrical systems on the U.S. Navy's next-generation all-electric ships (AES) creates significant new challenges in the area of total-ship energy management. Power intensive assets are likely to compete for available generation capacity, and thermal loads are expected to greatly exceed current heat removal capacity. To address this challenge, a total-ship zonal distribution model that includes electric power, chilled water (CW), and refrigerated air (RA) systems is developed. Classifier-guided sampling (CGS), a population-based optimization algorithm for solving problems with discrete variables and discontinuous responses, is used to identify high-performance configurations with respect to fuel consumption. This modeling approach supports early-stage design decisions and performance analyses of notional systems in response to changing operating modes and damage scenarios. A set of configurations that enhance survivability is identified. Results of a comparison study demonstrate that CGS improves the rate of convergence toward superior solutions, on average, when compared to genetic algorithms (GAs).

Analysing differences between algorithm configurations through ablation

Developers of high-performance algorithms for hard computational problems increasingly take advantage of automated parameter tuning and algorithm configuration tools, and consequently often create solvers with many parameters and vast configuration spaces. However, there has been very little work to help these algorithm developers answer questions about the high-quality configurations produced by these tools, specifically about which parameter changes contribute most to improved performance. In this work, we present an automated technique for answering such questions by performing ablation analysis between two algorithm configurations. We perform an extensive empirical analysis of our technique on five scenarios from propositional satisfiability, mixed-integer programming and AI planning, and show that in all of these scenarios more than 95 % of the performance gains between default configurations and optimised configurations obtained from automated configuration tools can be explained by modifying the values of a small number of parameters (1–4 in the scenarios we studied). We also investigate the use of our ablation analysis procedure for producing configurations that generalise well to previously-unseen problem domains, as well as for analysing the structure of the algorithm parameter response surface near and between high-performance configurations.

Step-up Transformerless Seven-level DC-AC Hybrid Topology for Interconnection of Renewable-based DC Sources to Microgrids

This article introduces a new step-up transformerless multi-level DC-AC hybrid topology for interconnecting renewable DC sources to loads or microgrids. This enabling technology incorporates the best characteristics of three modified basic topologies—a DC-DC multi-level boost converter, a DC-DC multi-level buck converter, and an H-bridge—to obtain a seven-level step-up DC-AC hybrid structure using only one DC input and nine power switches for a single-phase output with field-programmable gate array based control. The advantages of the step-up seven-level structure compared to other proposals are higher efficiency, a reduced number of power switches, and high power density associated with transformerless characteristic. Furthermore, in contrast to conventional topologies, the proposed design does not require voltage/current monitoring of the capacitors or a capacitor-balancing control scheme, and only one DC source input is used. Consequently, a high-performance configuration is obtained. The laboratory results demonstrate the validity of the design and the performance of the prototype.

Wind Energy Conversion Based on Matrix Converter

In recent years renewable sources such as solar, wave and wind are used for the generation of electricity. Wind is one of the major renewable sources. The amount of energy from a Wind Energy Conversion System (WECS ) depends not only on the wind at the site, but also on the control strategy used for the WECS. In assistance to get the appropriate wind energy from the conversion system, wind turbine generator will be run in variable speed mode. The variable speed capability is achieved through the use of an advanced power electronic converter. Fixed speed wind turbines and induction generators are often used in wind farms. But the limitations of such generators are low efficiency and poor power quality which necessitates the variable speed wind turbine generators such as Doubly Fed Induction Generator (DFIG) and Permanent Magnet Synchronous Generator (PMSG). A high-performance configuration can be obtained by using Scherbius drive composed of a DFIG and a converter in combination AC-DC-AC connect between stator & rotor points for providing the required variable speed operation. DOI: http://dx.doi.org/10.11591/ijpeds.v5i1.6025

Jmodeltest.org: selection of nucleotide substitution models on the cloud

Summary: The selection of models of nucleotide substitution is one of the major steps of modern phylogenetic analysis. Different tools exist to accomplish this task, among which jModelTest 2 (jMT2) is one of the most popular. Still, to deal with large DNA alignments with hundreds or thousands of loci, users of jMT2 need to have access to High Performance Computing clusters, including installation and configuration capabilities, conditions not always met. Here we present jmodeltest.org, a novel web server for the transparent execution of jMT2 across different platforms and for a wide range of users. Its main benefit is straightforward execution, avoiding any configuration/execution issues, and reducing significantly in most cases the time required to complete the analysis.Availability and implementation: jmodeltest.org is accessible using modern browsers, such as Firefox, Chrome, Opera, Safari and IE from http://jmodeltest.org. User registration is not mandatory, but users wanting to have additional functionalities, like access to previous analyses, have the possibility of opening a user account.Contact: info@jmodeltest.org

Electrical Power Grid Network Optimisation by Evolutionary Computing

A major factor in the consideration of an electrical power network of the scale of a national grid is the calculation of power flow and in particular, optimal power flow. This paper considers such a network, in which distributed generation is used, and examines how the network can be optimized, in terms of transmission line capacity, in order to obtain optimal or at least high-performing configurations, using multi-objective optimisation by evolutionary computing methods.

Computational and mathematical modeling of the effects of tailbeat frequency and flexural stiffness in swimming fish

In this paper we describe how we combine computational and mathematical models to form virtual fish to explore different hypotheses about the impact of centra. We show how we create simulation models using a combination of a mathematical model of a fish-like robot using caudal fin propulsion, a propulsion model, and an optimizer, to explore the impact of centra under various scenarios. The optimizer uses the mathematical model to construct valid configurations of the digital robot and uses the utility function and propulsion model to evaluate the performance of each configuration. The evaluations are used to explore the adaptive landscape and find high-performing configurations. Our results show that the high-performing configurations have both increased (flexural) stiffness of the tail and higher tailbeat frequencies.