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Being the key sensitive elements of the micro-electromechanical systems (MEMS) resonant sensors, performance of the double-ended tuning fork (DETF) will affect precision of the whole sensor greatly. Currently, most of the research on DETF is concentrated on ideal theory or simply mentioned as part of the sensor. But, in most engineering occasions, there exists many factors such as the additional mass, air damping and fabrication process, etc. However, few references are individually aimed at the mechanical characters of DETF. To choose the suitable DETF, it is important to solely research and measure the performance of this element.

In this paper, the authors combine the practical engineering applications and deduce the calculation method of sensitive element’s resonant frequency under various circumstances. The authors also design a force-generating system to make the loading simulation and verify the correctness of theory.

On the basis of Euler–Bernoulli theory and Rayleigh’s equation, frequency theories of DETF under four different situations have been deduced. A force-generating device is designed and fabricated to measure the mechanical characters of the DETF. The experiments using force-generating system, DETF, the high performance laser vibrometer and oscillograph are carried out. It verifies the correctness of theory.

Currently, most of the research on DETF is concentrated on ideal theory or simply mentioned as part of the sensor, and few references are individually aimed at the mechanical characters of DETF. Combining the practical engineering applications, the authors deduced the frequency theories of DETF. A force-generating system is designed and fabricated to measure the mechanical characters of the DETF, and the experiment results match the theoretical results very well.

Presents a framework for deciding on a good execution strategy for a given program based on the available data and task parallelism in the program on PC laboratory clusters. Proposes a virtual cluster scheduling scheme to take account of the relationships between tasks for task parallelism, and also processor speed, processor load and network environment to balance load for data parallelism in a PC cluster environment. The approach is very effective in terms of the overall execution time, and demonstrates the feasibility of automatic cluster assignment, processor set selection and data partition functions for data and task parallel programs.

A specially designed hydraulic power pack is providing the motive power to test landing and deck handling systems on the Royal Navy's newest helicopter, the EH101 Merlin, developed jointly by Westland Helicopters in the UK and Agusta of Italy.

The evaluation of linear dynamic response analysis of large structures by vector superposition requires, in its traditional formulation, the solution of a large and expensive eigenvalue problem. A method of solution based on a Ritz transformation to a reduced system of generalized coordinates using load dependent vectors generated from the spatial distribution of the dynamic loads is shown to maintain the high expected accuracy of modern computer analysis and significantly reduces the execution time over eigensolution procedures. New computational variants to generate load dependent vectors are presented and error norms are developed to control the convergence characteristics of load dependent Ritz solutions. Numerical applications on simple structural systems are used to show the relative efficiency of the proposed solution procedures.

Long-term reliability analysis of generation capacity based on the forecasted load demand helps to identify the optimal generation expansion plan of the system. This paper analyzes the generation adequacy of Mexico’s National Interconnected Power System (MNIPS) using loss of load expectation (LOLE) and loss of energy expectation (LOEE) indices.

These indices are calculated through an analytical (recursive) method and are then compared with values recommended by the North American Electric Reliability Council (NERC). Weekly indices are computed to analyze the load curtailment options that may occur in some periods.

Forecasted values, including load and generation capacity considering maintenance schedules, additions of new generating units and permanently shut down units in accordance with the long-term expanding-system plan have been considered. The load forecast uncertainty is also included.

This is original work.

The purpose of the paper is to analyze the effect on centralized dispatching generation cost under the condition where the single‐buyer electric supply industry (ESI) with independent power producer (IPP) scheme (the ESI structure that is widely implemented in developing countries) is opened for bilateral trading. The analysis is based on the Thai power system.

The analysis considers the average generation cost (B/kWh) derived from unit commitment of power generation under three cases – single‐buyer model with must‐run IPP scheme, unconstrained operation case, and the case where bilateral trading is introduced. The analysis is performed for different demand levels.

The results indicate that the operational constraint from the virtual must‐run power purchase agreement under IPP scheme leads to higher generation cost. The choice of allowing IPP to trade through bilateral trading and removal of the must‐run contract shows potential to lessen the operational constraint and lower generation cost can be achieved under some conditions – depending on the plant type and the share of bilateral market in the system. The planning and policy should take into consideration these conditions especially during the transitional period of ESI reform.

The main limitation of the analysis is the availability to recent data. The load factor of the demand curve is taken from the peak day of the year, resulting in higher load factor than the average of Thailand. With lower load factor, the must‐run constraints might be more obvious during the lighter load day and more expensive generation cost can be observed. However, the cases are compared at same demand curve. Therefore, the trend of result will lead to the same conclusion.

Uneconomic operation of the single‐buyer ESI with IPP scheme which has been implemented in many developing countries was clearly determined. The literature shows that the ESI operation can be more efficient when the sector moves towards higher degree of competition, either fully competitive market or bilateral trading. The potential for better operating conditions for bilateral trading has been suggested. The simulation based on the power system of Thailand can be an example for other developing countries operating under the similar ESI structure.

The purpose of this paper is to propose Extensible Markup Language (XML) data partitioning schemes that can cope with static and dynamic allocation for parallel holistic twig joins: grid metadata model for XML (GMX) and streams‐based partitioning method for XML (SPX).

GMX exploits the relationships between XML documents and query patterns to perform workload‐aware partitioning of XML data. Specifically, the paper constructs a two‐dimensional model with a document dimension and a query dimension in which each object in a dimension is composed from XML metadata related to the dimension. GMX provides a set of XML data partitioning methods that include document clustering, query clustering, document‐based refinement, query‐based refinement, and query‐path refinement, thereby enabling XML data partitioning based on the static information of XML metadata. In contrast, SPX explores the structural relationships of query elements and a range‐containment property of XML streams to generate partitions and allocate them to cluster nodes on‐the‐fly.

GMX provides several salient features: a set of partition granularities that balance workloads of query processing costs among cluster nodes statically; inter‐query parallelism as well as intra‐query parallelism at multiple extents; and better parallel query performance when all estimated queries are executed simultaneously to meet their probability of query occurrences in the system. SPX also offers the following features: minimal computation time to generate partitions; balancing skewed workloads dynamically on the system; producing higher intra‐query parallelism; and gaining better parallel query performance.

The current status of the proposed XML data partitioning schemes does not take into account XML data updates, e.g. new XML documents and query pattern changes submitted by users on the system.

Note that effectiveness of the XML data partitioning schemes mainly relies on the accuracy of the cost model to estimate query processing costs. The cost model must be adjusted to reflect characteristics of a system platform used in the implementation.

This paper proposes novel schemes of conducting XML data partitioning to achieve both static and dynamic workload balance.

A cascaded observer-based transfer delay frequency locked loop (CODFLL) algorithm is developed to control the distribution static compensator (DSTATCOM) to address various power quality (PQ) issues arise because of distorted grid and load conditions. Moreover, frequency locked loop is included along with the observer to take care of the frequency drift from nominal value and to improve its performance during steady state and transient conditions. During daylight, the proposed system works as photovoltaic (PV) DSTATCOM and performs multiple functions for improving PQ whilst transferring power to grid and load. The system under consideration acts as DSTATCOM during night and bad weather condition to nullify the PQ issues.

CODFLL control algorithm generates reference signal for hysteresis controller. This reference signal is compared with an actual grid signal and a gate pulse is produced for a voltage source converter. The system is made frequency adaptive by transfer delay adaptive frequency locked loop (FLL). Peak power is extracted from a PV source using the perturb and observe technique irrespective of disturbances encountered in the system.

The PV system’s performance with the proposed controller is studied and compared with conventional control algorithms such as least mean fourth (LMF), improved second-order generalized integrator frequency locked loop (ISOGI-FLL), synchronous reference frame phased lock loop (SRF-PLL) and frequency adaptive disturbance observer (DOB) for different cases, for example, steady-state condition, dynamic condition, variable insolation, voltage sag and swell and frequency wandering in the supply side. It is found that the proposed method tracks the frequency variation faster as compared to ISOGI-FLL without any oscillations. During unbalanced loading conditions, CODFLL exhibits zero oscillations. Harmonics in system parameters are reduced to the level of IEEE standard; unity power factor is maintained at the grid side; hassle-free power flow takes place from the source to the grid and load; and consistent voltage profile is maintained at the coupling point.

CODFLL control algorithm is developed for PV-DSTATCOM systems to generate a reference grid current.

The purpose of this paper is to deal with the problem of symmetrization of asymmetrical three‐phase delta connected nonlinear load. In the model of the three‐phase sinusoidal voltage source have also been included inner impedances. The purpose is to obtain symmetrical line currents of the voltage source, to minimize RMS values of currents and to minimize higher harmonics generated by nonlinear loads.

This symmetrization of the system is realized by means of a symmetrizing system, which is composed of LC one‐ports. In order to solve the problem the symmetrical component theory is applied. The structure of symmetrizing system is consisted of two components: parameters determined for the basic harmonic and the filter for elimination of the higher harmonics generated by nonlinear loads.

After symmetrization line currents of the source will be symmetrical with lower RMS values than before symmetrization, and the source will generate the greater active power than beforehand.

This approach can be used for inertialess (non‐reactive) elements in systems, where currents are periodical.

The results of symmetrization can be useful for high‐power systems where LC one‐ports can be used, e.g. for arc furnaces.

Application of presented methods makes possible to improve the working point of the system, i.e. voltage source can generate greater active power than before symmetrization and line currents can be symmetrical.

This study proposes targeted modernization of the Department of Defense (DoD's) Joint Forces Ammunition Logistics information system by implementing the optimized innovative information technology open architecture design and integrating Radio Frequency Identification Device data technologies and real-time optimization and control mechanisms as the critical technology components of the solution. The innovative information technology, which pursues the focused logistics, will be deployed in 36 months at the estimated cost of $568 million in constant dollars. We estimate that the Systems, Applications, Products (SAP)-based enterprise integration solution that the Army currently pursues will cost another $1.5 billion through the year 2014; however, it is unlikely to deliver the intended technical capabilities.