Defined Performance Indices Research Articles

Hyperthyroidism therapy: What can decision support systems already achieve?

AbstractCurrently, only a few theoretical support systems exist for the treatment of hyperthyroidism. They are typically not practically applicable and solely focus on Graves’ disease. The recently developed DigiThy software framework can be used to assist physicians for methimazole dose titration during the treatment of Graves’ disease. In this study, a pool of 60 virtual patients was created to compare physicians’ individual treatment approaches by 8 different physicians and students (including three colleagues, unexperienced with care of Graves’ disease) with the decision support system DigiThy in terms of already defined performance indices. These indices are used to assess the deviation of FT4 from the reference range throughout the treatment. The computer aided treatment algorithms outperformed the usual care approach according to different prespecified criteria for treatment success. Two out of the three unexperienced colleagues improved their treatment success over time, i.e. with more patients treated. In conclusion, our findings suggest that the DigiThy software may be a useful tool for use as a decision support system in routine care of patients with Graves’ disease, while also serving as an effective training tool for the education of physicians. Randomized controlled studies are required before implementation of DigiThy in daily clinical practice.

Rate adaptation performance and quality analysis of adaptive HTTP streaming methods

Media streaming is the key innovation in technology era brings high quality on-demand and live media content to the consumer on-the-go anywhere, any time. Achieving best quality-of-service and quality-of-experience (QoE) are major concerns in the current circumstances due to increasing network usage and user demand to high quality media content. Conventional streaming approaches face numerous challenges in delivering media content to the uses without degradation of quality. An adaptive HTTP streaming is emerging content delivery approach which provides real time content delivery without compromising quality and ensuring superlative QoE. The dynamic and robust bit rate selection based on the network and client key performance indices helps to achieve best class of service to the consumer. As many standards and processes emerge in the field of Adaptive HTTP Streaming, it is necessary to study and compare the performance of different approaches based on the defined metrics. In this paper, we emphasis on the comprehensive study of different emerging adaptive streaming models such as HTTP Live Streaming, Microsoft Smooth Streaming and MPEG Dynamic Adaptive Streaming over HTTP (DASH). The experiments were conducted using Gstreamer adaptive HTTP streaming client to measure delivery performance of the approaches under varying network conditions for on-demand streaming and live streaming contents. The outcome for adaptive HTTP methods were measured and analyzed using defined performance indices. The analyzed data indicates that each delivery method performs well with respect to outlined metrics. However, overall DASH gives considerably stable performance across different network settings than other streaming approaches.

Analysis and prediction of vulnerability in smart power transmission system: A geometrical approach

The paper proposes a novel methodology to analyze and measure the impact of line tripping on grid vulnerability which may lead to cascade failure in smart power transmission system. The key contributions are analysis of current flow path and identification of critical line from normal to perturbed grid with the knowledge of grid topology. To achieve this two performance indices i.e. power flow index and vulnerability index have been defined on the bases of geometry of current flow path. A power flow index is defined to analyze impact of topological changes on current flow path and identify underloaded and overloaded lines. Probability of the critical line and the location of vulnerability center are identified by the vulnerability index. Analytically defined performance indices are applied analyzed and validate using the benchmark IEEE 30 bus power system. The critical line identified by proposed indices is also verified with the probabilistic framework. The proposed methodology allows to focus attention on the power grid vulnerable areas and can help the control system operator to investigate the changes in power flow on transmission lines and initiate the necessary corrective action. The methodology proposed in this paper can be used in security assessment and centralized monitoring of power flow in future smart grid wide area monitoring protection and control system.

Experimental Study on the Reaction Conditions of a Methanol Steam Reforming Process

Abstract The effects of various reaction conditions on a methanol steam reforming (MSR) process were analyzed in this paper by adopting design of experiment (DOE) techniques. The control factors considered are the length and the temperature of the catalyst bed, the steam-to-carbon ratio and the space velocity of the feedstocks, and the catalyst loading within the MSR reactor. The performance indices (quality characteristics) to be analyzed are the methanol conversion, the hydrogen production rate, the CO concentration in the produced mixture, and the ratios of the hydrogen production rate to the methanol feed rate and the catalyst loading, respectively. The major objective of the study is to analyze the holistic influences and the individual significance of the aforementioned reaction conditions on the defined MSR performance indices. Results suggest that temperature is the most significant factor that positively correlates the defined performance indices. The performance of a MSR reactor can be enhanced by raising the reacting temperature. Nonetheless, the CO concentration in the produced mixture is also increased. According to the present work, the effects of the reaction conditions on a MSR process can be analyzed simultaneously meanwhile the optimal combination of the concerned control factors can be obtained.

Modeling, evaluation, and optimization of gas-power and energy supply scenarios

Recently, renewable energy sources such as wind power and photovoltaic (PV) are receiving a wide acceptance because they are inexhaustible and nonpolluting. Renewable energy sources are intermittent ones because of climate changes in wind speed and solar irradiance. Due to the continuous demand growth and the necessity for efficient and reliable electricity supply, there is a real need to increase the penetration of gas technologies in power grids. The Canadian government and stakeholders are looking for ways to increase the reliability and sustainability of power grid, and gas-power technologies may provide a solution. This paper explores the integration of gas and renewable generation technologies to provide a qualified, reliable, and environmentally friendly power system while satisfying regional electricity demands and reducing generation cost. Scenarios are evaluated using four key performance indicators (KPIs), economic, power quality, reliability, and environmental friendliness. Various scenarios outcomes are compared based on the defined performance indices. The proposed scenario analysis tool has three components, the geographic information system (GIS) for recording transmission and distribution lines and generation sites, the energy semantic network (ESN) knowledgebase to store information, and an algorithm created in Matlab/Simulink for evaluating scenarios. To interact with the scenario analysis tool, a graphical user interface (GUI) is used where users can define the desired geographic area, desired generation percentage via gas technology, and system parameters. To evaluate the effectiveness of the proposed method, the regional zone of the province of Ontario and Toronto are used as case studies.

H02 Behavioural Dysexecutive Disorders In Huntington's Disease

<h3></h3> Dysexecutive symptoms such as apathy, impulsivity and distractibility have been reported on clinical ground in HD. However previous studies have assessed dysexecutive behavioural disorders using clinical interview or nonspecific questionnaires incorporating other features resulting in highly variable evaluation with poorly defined performance indices. This study aimed to assess dysexecutive behavioural abnormalities in HD, using a validated instrument, the Behavioural Dysexecutive Syndrome Inventory (BDSI). 14 patients (mean age: 55.5 years; SD 12.4; range: 34–73; mean duration: 8.7 years; SD=7; range: 2–30; mean MMSE score: 25; SD=3.4) with clinically diagnosed and genetically confirmed HD, were included. The assessment of depressive symptoms (Montgomery Asberg Depression Scale) showed a mild depression in 7 patients. The BDSI is a highly structured caregiver based interview which rates frequency and severity of 12 dysexecutive disturbances (global hypoactivity with apathy, hyperactivity, irritability-impulsivity, euphoria, perseverative behaviour; environmental dependency, social behaviour disorders). The analysis of individual performance was performed using cutoff scores at the 5% level using normative data obtained in 96 controls¹. The prevalence of behavioural dysexecutive syndrome was high (50%; 95% CI: 24–76). The behavioural profile was characterised by the prominence of irritability (50%), hyperactivity (43%), apathy (29%), disinterest (22%) and difficulties for anticipation (14%). This study based on the BDSI revealed in HD that behavioural dysexecutive disorders are: 1 frequent with a prevalence of 50%, 2 characterised by a specific profile with the prominence of irritability and hyperactivity-distractibility, 13 whereas the hypoactivity-apathy disorders were less frequent contrary to most other degenerative disorders. 1 Godefroy <i>et al</i>. Ann Neurol. 2010

Optimal shifting of Photovoltaic and load fluctuations from fuel cell and electrolyzer to lead acid battery in a Photovoltaic/hydrogen standalone power system for improved performance and life time

Cost reduction is very critical in the pursuit of realizing more competitive clean and sustainable energy systems. In line with this goal a control method that enables minimization of the cost associated with performance and life time degradation of fuel cell and electrolyzer, and cost of battery replacement in PV/hydrogen standalone power systems is developed. The method uses the advantage of existing peak shaving battery to suppress short-term PV and load fluctuations while reducing impact on the cycle life of the battery itself. This is realized by diverting short-term cyclic charge/discharge events induced by PV/load power fluctuations to the upper band of the battery state of charge regime while operating the fuel cell and electrolyzer systems along stable (smooth) power curves. Comparative studies of the developed method with two other reference cases demonstrate that the proposed method fares better with respect to defined performance indices as fluctuation suppression rate and mean state of charge. Modeling of power electronics and design of controllers used in the study are also briefly discussed in Appendix A.

Assessing circuit breaker performance using condition-based data and Bayesian approach

This paper proposes a methodology to assess the performance of circuit breaker utilizing its control circuit data. Various performance indices are defined to assess the condition of breaker using probability distributions. Bayesian updating approach is implemented to update these indices as the new data becomes available. An approximation in implementing the Bayesian approach to deal with large amounts of data on-line is considered. The methodology is applied to data recorded at different times during both open and close operations on a group of similar circuit breakers. The methodology can be used to quantify the effect of maintenance making use of the defined performance indices, which further helps in developing system level risk-based decision approaches for maintenance optimization.

Performance analysis and comprehensive index optimization of a new configuration of Stewart six-component force sensor

This paper proposes a new configuration of six-component force/torque sensor based on Stewart platform, and discusses the performance analysis and comprehensive index optimization of the six-component force sensor. Based on the classical Stewart platform-based force sensor, a modified sensor structure is proposed, and their statics mathematical models are built by using the screw theory. The condition number and generalized amplifying coefficient defined by singular values of force Jacobian matrix are used to evaluate the performance of sensor, such as isotropy, sensitivity, stiffness, etc. The effect of spherical joint frictional moment on the sensor is established by using the related force mapping matrix. With the combination of the defined performance indices, the comprehensive index optimization of the structural parameters of the modified Stewart six-component force sensor is achieved by using the indices atlases and genetic algorithm. The research results of the paper are useful for the design and further research of the six-component force sensor.

A hierarchical control protocol for group-oriented playbacks supported by content distribution networks

Content distribution networks have recently been introduced as a more efficient alternative to centralized servers for the delivery of static content as well as media streaming services ranging from TV broadcasts to video on-demand. Content Distribution Networks can also efficiently provide collaborative playback service, which allows a synchronous group of users to select, simultaneously watch altogether and share the control of a multimedia session. This paper presents the definition and analysis of the Hierarchical Cooperative Control Protocol (HCOCOP), which allows a synchronous group of users to share the control of the media streaming session provided by a Content Distribution Network. The analysis phase, which was supported by discrete-event simulation, was carried out to characterize the efficiency of the protocol on the basis of the following defined performance indices: blocking probability, denial probability, server load and network load. The performances obtained for architectures based on Content Distribution Networks are compared with those obtained for centralized architectures providing collaborative playbacks. The comparison shows that HCOCOP significantly improves performance of media streaming control.

An optimal design method for improving the lightning performance of overhead high voltage transmission lines

This paper presents a method for the optimal design of high voltage transmission lines taking into consideration shielding and backflashover failure rates. The minimization of suitably defined performance indices, which relate the failures caused by lightning in a transmission line to both line insulation level and tower footing resistance, is aimed. Optimum values for both line insulation level and tower footing resistance are calculated. The method is applied on several operating Hellenic transmission lines of 150 and 400 kV, respectively, carefully selected among others, due to their high failure rates during lightning thunderstorms. Special attention has been paid on open loop lines, where a possible failure could bring the system out of service causing significant problems. The obtained design parameters, which reduce the failure rates caused by lightning, are compared with the existing design parameters of the transmission lines leading up to useful conclusions. The proposed optimization method can be proved a valuable tool to the studies of electric power systems designers, intending to reduce the failure rates caused by lightning.

Modelling of hydrogen transfer in coal hydroliquefaction: 6. Relative rate constants of hydrogen transfer from hydroaromatic solvents to radicals generated by thermolysis of benzylphenylether

A method based on competitive kinetics is employed for measuring relative rate constants for hydrogen transfer from four H-donor solvents (9,10-dihydrophenanthrene, tetralin, indan and 1,2,3,4-tetrahydroquinoline), for the stabilization of free radicals generated by thermal decomposition of benzylphenylether at 300 and 400 °C. These relative rates are slightly different and are of the same order of magnitude as the values obtained for the liquefaction of bituminous Freyming coal. It appears that the previously defined performance indices are more suitable than the relative rate constants for classifying these hydroaromatic solvents.

An algorithm for optimum control of static VAR compensators to meet phase-wise unbalanced reactive power demands

The operation of thyristor-controlled static VAR compensators (SVCs) at various conduction angles can be used advantageously to meet the unablanced reactive power demands in a system. However, such operation introduces harmonic currents into the AC system. This paper presents an algorithm to evaluate an optimum combination of the phase-wise reactive power generations from SVC and balanced reactive power supply from the AC system, based on the defined performance indices, namely, the telephone influence factor ( TIF ), the total harmonic current factor ( IT ) and the distortion factor ( D ). Results of the studies conducted on a typical distribution system are presented and discussed.

Approach to the performance evaluation and tuning of communication protocol implementation

An approach to the performance evaluation of a communication protocol operating in a concurrent environment is described. The method defines suitable performance indices and outlines the implementation of a software monitor embedded in the protocol. The defined performance indices allow the protocol performance to be evaluated both in the adopted implementation and with regard to the application requirements.