Service Performance Characteristics Research Articles

Stress prediction of bridges using ANSYS soft and general regression neural network

Bridge managers are often eager to identify the carrying capacities and service performance characteristics of bridge structures. In view of the massive number of bridges managed and maintained in China, providing a quick evaluation of bridge performance bridges has become an urgent challenge for bridge engineering. Aiming at many adverse problems of bridge load tests, such as their high costs, long time consumption, low efficiency, impact on traffic, and damage to bridge structures, a new method for bridge static behavior prediction is proposed herein, based on dynamic load test data. The method adopts a generalized regression neural network algorithm with fast convergence and a nonlinear approximation, determines the sensitive parameters based on a full-bridge sensitivity analysis, forms training samples using a uniform design sampling method, and establishes intelligent agent model. The initial finite element analysis model of the bridge structure is updated using the proposed proxy model and dynamic load test data, and the static behavior of the existing bridge structure is accurately predicted based on the updated finite element model. To verify the correctness of the proposed method, a practical bridge is considered as the research object, and the static response of the bridge structure is predicted. The predicted results are consistent with the static load test results for the bridge, verifying the correctness of the proposed method. The results show that the maximum error between the theoretical calculation result and measured value is only 4.34% and the minimum error is only 3.52%. The strain prediction results are consistent with the measured results, and the modified theoretical analysis model provides high accuracy for strain prediction results under different working conditions. The application in practical engineering shows that the prediction results under different load conditions are adaptable and highly accurate.

Effect of fine particle peening on surface integrity of flexspline in harmonic drive

High-performance precision gear drives such as harmonic gear have high requirements on tooth profile accuracy, surface quality, fatigue life and other service performance characteristics, which urgently needs an effective surface strengthening method. This work aims to examine the feasibility and effectiveness of fine particle peening (FPP) treatment on surface integrity of flexspline in harmonic drive precision transmission. To this end, FPP process experiments were carried out, and this process was simulated based on a coupling method of discrete element method and finite element method (DEM-FEM) considering the kinematic hardening behavior of the material. The simulation results were in good agreement with the test results. Effects of shot peening pressure, injection velocity, material properties and tooth profile on surface roughness and induced residual stress of the target flexspline were analyzed. The results reveal that after FPP, the amplitude of residual compressive stress of the flexspline can reach 470 MPa, and the surface roughness Sa becomes approximately 0.5 μm. For precision gears with low hardness such as flexspline in harmonic drive, it is suggested to adopt FPP with low air pressure to achieve both saturated residual compressive stress and lower surface roughness, thus benefitting enhanced fatigue life.

Healthcare needs of vulnerable patient groups: available data and existing gaps in Germany with respect to long-term mechanical ventilation.

AimLong-term invasively ventilated patients exhibit exceptional and resource-intensive healthcare needs. However, major knowledge gaps in Germany complicate appropriate approaches to best address these demands. This paper evaluates available information on the patient group and their healthcare needs from German data sources and derives implications for healthcare planning and regulation by national/federal self-governing bodies, political decision-makers, and specialized providers.MethodsBased on the concept of needs, we addressed the normative dimension typically characterized by epidemiological data. Based on existing German health system data resources, an explorative approach was utilized to identify and characterize available databases providing information on the patient group and/or their healthcare.ResultsTo date, no available database provides information on the healthcare needs of this patient group. As of the reporting year 2017, the diagnosis-related groups (DRG) statistics will provide hospital-specific data on home invasive ventilation interventions, but the data do not provide information on long-term care. Claims data may be a promising source for cross-sectoral evaluation of healthcare needs but feature methodological challenges. These results call for efforts to address limited data eligibility, adopt a broader understanding of healthcare needs, and identify actions needed to evidence informed and needs-oriented healthcare.ConclusionFuture approaches on needs-oriented specialized healthcare should close the existing knowledge gap based on reliable data. In addition to normative information, they should consider subjective dimensions on a life course perspective and quantitative and qualitative service performance characteristics across multiple sectors and professions.

Access to Device Reachability Data as a Component of Horizontal M2M Service Platform

The variety of Machine-to-Machine (M2M) applications based on very heterogeneous forms of platforms, technology, and data models has resulted in vertical solutions where interoperability is very limited. In order to develop horizontal platforms across different business domains, networks and devices, it is necessary to outline generic capabilities. Service Capabilities provide data mediation functions that may be shared by different applications through application programming interfaces. The paper presents an approach to design RESTful Web Services for access to location and presence status information of M2M devices. The Device Reachability Service Capability provides access to device location and allows device presence information to be registered and obtained. Web Service operations are identified by analysis on typical use cases. M2M device reachability information is modelled as REST resources organized in a tree structure. Web Service performance characteristics are evaluated by simulation.

Experimentally driven quality of experience‐aware multimedia content delivery in modern wireless networks

SummaryIn this paper, a holistic approach for supporting Quality of Experience (QoE)‐aware multimedia content delivery to modern wireless networks is described. The introduced Dynamic User Experience framework, founded on network utility maximization theory, allows mobile users to express their preference with respect to the instantaneous experience of their service performance, through the dynamic adaptation of their service‐aware utility functions. By developing and exploiting an Android‐based mobile multimedia application prototype capable of capturing users' quality perception with respect to multiple psychological and networking factors, an efficient correlation of users' QoE and service performance characteristics is derived. Based on real user data obtained through experimentation, we are able to quantify appropriately defined QoE‐aware utility functions that can be used throughout the overall radio resource management process. Extensive numerical results verify our analytical claims on the efficacy and applicability of the proposed framework in a heterogeneous wireless environment, significantly optimizing mobile Internet experience. Copyright © 2015 John Wiley & Sons, Ltd.

Bus Travel Time Deviation Analysis Using Automatic Vehicle Location Data and Structural Equation Modeling

To investigate the influences of causes of unreliability and bus schedule recovery phenomenon on microscopic segment-level travel time variance, this study adopts Structural Equation Modeling (SEM) to specify, estimate, and measure the theoretical proposed models. The SEM model establishes and verifies hypotheses for interrelationships among travel time deviations, departure delays, segment lengths, dwell times, and number of traffic signals and access connections. The finally accepted model demonstrates excellent fitness. Most of the hypotheses are supported by the sample dataset from bus Automatic Vehicle Location system. The SEM model confirms the bus schedule recovery phenomenon. The departure delays at bus terminals and upstream travel time deviations indeed have negative impacts on travel time fluctuation of buses en route. Meanwhile, the segment length directly and negatively impacts travel time variability and inversely positively contributes to the schedule recovery process; this exogenous variable also indirectly and positively influences travel times through the existence of signalized intersections and access connections. This study offers a rational approach to analyzing travel time deviation feature. The SEM model structure and estimation results facilitate the understanding of bus service performance characteristics and provide several implications for bus service planning, management, and operation.

Implementing viscoelastic rheological methods to evaluate low temperature performance of modified asphalt binders

In this research, the effects of four modifiers including crumb rubber, gilsonite, styrene–butadiene–styrene (SBS) and polyphosphoric acid (PPA) on the mechanical and rheological properties of asphalt binder at low service temperature are investigated. The main objective of this paper is to rank modifiers due to their effect on low service performance characteristics of asphalt binder for all type and extent of observed modified asphalt binders. For this purpose, the bending beam rheometer (BBR) test is performed on different extent of modifiers at five temperatures: −6°C, −12°C, −18°C, −24°C and −30°C. Asphalt binder is categorized as a viscoelastic material. Among several linear viscoelastic models, the Burgers model is selected for describing the mechanical behavior of modified asphalt binders. Four Burgers parameters are calculated by means of the principle of multiple non-linear regression and then these parameters are used for comparing the performance of asphalt binders by these three approaches: SuperPAVE Performance Grading (PG) protocol, dissipated energy ratio and derivation of creep compliance. Utilizing these three approaches, modified asphalt binders are ranked based on higher quantity of low temperature, dissipated energy ratio and derivation of creep compliance for all type and extent of modifiers alongside. Results show that each approach produces a particular grading which is not same as another one. In spite of variation of rankings, among the all evaluated modified asphalt binders, crumb rubber modified asphalt binder totally shows superior performance on low service temperature in all three methods.

The Optimized Design for Groove Parameters Based on Cement Pavement Materials Performance

Aiming at the service performance characteristics of cement concrete pavement, this paper puts forward optimized design concept for groove parameters of cement pavement. Single groove parameter optimal choice is systematically analyzed based on integrated service quality of cement pavement. Through a variety of multi-contrast laboratory tests and theoretical analysis, from three aspects of anti-slide, strength, and noise reduction, optimized design scheme of groove parameters are demonstrated and proposed, and groove parameters and form suitable for environment characteristics in seasonal frozen region are given.

Measuring and characterizing end-to-end Internet service performance

Fundamental to the design of reliable, high-performance network services is an understanding of the performance characteristics of the service as perceived by the client population as a whole. Understanding and measuring such end-to-end service performance is a challenging task. Current techniques include periodic sampling of service characteristics from strategic locations in the network and instrumenting Web pages with code that reports client-perceived latency back to a performance server. Limitations to these approaches include potentially nonrepresentative access patterns in the first case and determining the location of a performance bottleneck in the second.This paper presents EtE monitor, a novel approach to measuring Web site performance. Our system passively collects packet traces from a server site to determine service performance characteristics. We introduce a two-pass heuristic and a statistical filtering mechanism to accurately reconstruct different client page accesses and to measure performance characteristics integrated across all client accesses. Relative to existing approaches, EtE monitor offers the following benefits: i) a latency breakdown between the network and server overhead of retrieving a Web page, ii) longitudinal information for all client accesses, not just the subset probed by a third party, iii) characteristics of accesses that are aborted by clients, iv) an understanding of the performance breakdown of accesses to dynamic, multitiered services, and v) quantification of the benefits of network and browser caches on server performance. Our initial implementation and performance analysis across three different commercial Web sites confirm the utility of our approach.

The manufacturing TQM and service quality literatures: synergistic or conflicting paradigms?

Compares, contrasts and assimilates the contributions of the TQM manufacturing and service quality management literatures. A manufacturing model of TQM is proposed, and then developed and enhanced in the light of concepts, tools and techniques which have emerged from the service quality literature. Examination of the core TQM precepts in the light of the service literature highlights certain key asymmetries and differences between the manufacturing and service literatures on quality management, both being characterised by different strengths and weaknesses. While the manufacturing literature is practitioner oriented and highly evangelical and universally prescriptive in tone, the service quality management literature adopts a more measured and academically rigorous approach, although it is arguably less successful in generating practical solutions for management. While the service quality management literature has clearly been enriched and significantly influenced by the TQM manufacturing literature, it is now contributing to the conceptual development of the core precepts of TQM and nurturing a sensitivity to the contingencies which render their application appropriate. Indeed, as the performance characteristics of services increasingly contribute to the success of manufacturing organisations, the issue in future may well be the conceptual transferability of TQM from service to manufacturing.