Performance Assessment Analysis Research Articles

Seismic evaluation of rocking structures through performance assessment and fragility analysis

Numerical studies have been conducted for low- and medium-rise rocking structures to investigate their efficiency as earthquake-resisting systems in comparison with conventional structures. Several non-linear time-history analyses have been performed to evaluate seismic performance of selected cases at desired ground shaking levels, based on key parameters such as total and flexural story drifts and residual deformations. The Far-field record set is selected as input ground motions and median peak values of key parameters are taken as best estimates of system response. In addition, in order to evaluate the probability of exceeding relevant damage states, analytical fragility curves have been developed based on the results of the incremental dynamic analysis procedure. Small exceedance probabilities and acceptable margins against collapse, together with minor associated damages in main structural members, can be considered as superior seismic performance for medium-rise rocking systems. Low-rise rocking systems could provide significant performance improvement over their conventional counterparts notwithstanding certain weaknesses in their seismic response.

Analysis of Balance Scorecards Model Performance and Perspective Strategy Synergized by SEM

The performance assessment analysis after the economic crisis by using Balanced Scorecard (BSC) method becomes a powerful and effective tool and can provide an integrated view of the performance of an organization. This strategy led to the Indonesian economy being stretched positively after the economic crisis. Taking effective decisions is not spared from combining four BSC perspectives and strategies that focus on a system with different behavior or steps. This paper combines two methods of BSC with structural equation modeling (SEM)) because they have the same concept, which is a causal relationship, where the research model concept SEM variables use BSC variable. The purpose of this paper is to investigate the influence of variables that synergized between balanced scorecard with SEM as a means of strategic planning in the future. This study used primary data with a large enough sample to meet the maximum likelihood estimation by assessment scale of seven semantic points. This research model is a combination of one and two step models. The next step is to test the measurement model, structural equation modeling, and modification models. The test results indicated that the model has multi colinearities. Therefore, the model is converted into one step model. The test results after being modified into a model of the goodness of fit indices showed a good score. All BSC variables have direct significant influence, including the perspective of strategic goals and sustainable competitive advantage. The implication of the simulation model of goodness of fit-modification results are DF = 227, Chi-square =276.550, P =0.058, CMIN/DF = 1.150, GFI = 0.831, AGFI = 0.791, CFI = 0.972, TLI = 0.965 and RMSEA = 0.039.

Trainer's Choices in Teaching Translating/Interpreting

In spite of a relatively great variety of theoretical approaches to translation, translation theory mainly deals, irrespective of how elaborate it is, with fidelity to either the letter or the spirit of a message. The former type is described according to various particular approaches, as literal/semantic/documentary/overt/source language/source culture/author oriented translation while the latter is called communicative/instrumental/covert/cognitive/target language/target culture/reader oriented/ethnocentric translation. The choices discussed here refer to both translation theory and translation pedagogy. Thus, for an undergraduate course in translating/interpreting designed to meet both academic and vocational requirements a communicative translation model is chosen as theoretical background for a training focused on translation as an end product rather than on translation as a process. Mainly based on performance assessment and error analysis this training approach is meant to raise linguistic and cultural awareness and develop associated translational competences.

Mesophilic anaerobic co-digestion of waste activated sludge and Egeria densa : Performance assessment and kinetic analysis

Abstract The feasibility of anaerobic co-digestion of waste activated sludge (WAS) and grass Egeria densa ( E.d. ) with four different WAS: E.d. ratios was evaluated for the first time under mesophilic conditions. First-order kinetic, modified Gompertz, and Cone models were employed to reveal the principle kinetics of methane-rich bioenergy production from co-digestion. The results showed that the addition of E.d. could greatly upgrade the sludge methane production, and the highest methane yield averaged 198.32 ± 2.61 mL/g VS added for WAS: E.d. ratio of 0.7: 0.3, 18.72 ± 0.14% higher respective to that of WAS alone (about 176.36 mL/g VS added ). E.d. improved the solubilization of co-substrates and avoided the build-up of volatile fatty acids (VFAs) and free ammonia ([NH 3 ]) and subsequent inhibition, inducing a stable digestion environment. Model simulation indicated Cone model best fitted the actual evolution of methane production, as evidenced by low Root Mean Square Prediction Error (rMSPE) and Akaike’s Information Criterion (AIC), as well as high Pearson’s correlation between the predicated and actual values. Additionally, the parameters analysis highlighted that the co-digestion with E.d . substantially promoted the hydrolysis rate ( k hyd ) and methanogenesis potential ( f d ) of sludge, further explaining the increased solids removal and output of methane. This study demonstrated the sustainability and attractiveness of anaerobic co-digestion of sludge and grass E.d. , providing a sound basis for cost-efficient biomass stabilization and bioenergy recovery.

Maintenance management system for a defence aircraft development programme

Design and development of a defence aircraft involves solving of multi disciplinary problems over the development lifecycle. The ground and flight tests evaluation play a crucial role during the certification of the aircraft. The observations from the field trials viz. reported failures and corrective actions taken are of immense value for the performance assessment of aircraft. In addition to the aircraft performance assessment and root cause analysis of the failures, the data from the field also facilitates to assess and refine the maintenance procedures. This paper brings out a conceptual model of computerised aircraft maintenance management system (CAMMS), which is a product lifecycle management (PLM) enabled enterprise–wide solution involving designers, maintenance planners, test pilots, flight test engineers, inspectors and certification agency. This supposed system will encapsulate a framework for failure reporting analysis and corrective action that shall assist in failure, reliability and maintainability analysis, aiding a tighter control on the schedule and budgetary escalation.

Geochemical Modeling of Groundwater in Chinnar River Basin: A Source Identification Perspective

Understanding the geochemical evolution of groundwater is an essential part of the performance assessment and safety analysis of the geological system. Geochemical modeling techniques using PHREEQCI will aid in demarcating the main factors and mechanisms controlling the chemistry of groundwater. An attempt has been made in hard rock terrain of Chinnar basin, Dharmapuri district of Tamilnadu, India to interpret the processes and factors controlling hydrogeochemistry of groundwater. The area is made up of rock units belonging to Charnockite and Granitic Gneiss. Groundwater chemistry has been attempted based on laboratory observations of major cations like Na+, K+, Ca2+ and Mg2+and anions like Cl-, HCO3-, NO3-, F-, SO42-and PO43−. Piper diagram reveals higher bicarbonate, calcium and magnesium along the recharge zones and tend to decrease along the flow path and vice versa for ions like sodium, potassium and chloride. Two flow paths based on piper and saturation index were identified for two major lithounits. The granitic terrain shows precipitation of calcium and sulfate minerals and dissolution of silicate minerals. The charnockite terrain shows precipitation of silicates and dissolution of calcium and sulfate minerals. From initial to final solution slight variation in calcium and sulfate stability were identified but drastic change with reference to silicate minerals stability due to effective dissolution of silicate minerals from the litho units of the study area.

Performance assessment and hydrodynamic analysis of a submerged membrane bioreactor for treating dairy industrial effluent

Submerged membrane bioreactor (SMBR) is a relatively advanced technology for waste water treatment that involves integrated aerobic and anaerobic biological processes with membrane filtration. In the present investigation, hydrophobic polyvinylidene fluoride (PVDF) and hydrophilic polyacrylonitrile (PAN) hollow fiber (HF) membranes were tested in an indigenously fabricated SMBR for dairy effluent treatment under aerobic conditions using mixed microbial consortia. Effect of operating parameters such as suction pressure, degree of aeration and trans-membrane pressure (TMP) on membrane performance in terms of flux, rejection of turbidity, BOD and COD besides fouling characteristics was investigated. The observed optimum permeabilities of PVDF and PAN HF membranes were approximately 108 and 115LMHbar−1 with high extent of impurity removal. The rejection of COD was found to be 93% for PVDF and 91% for PAN HF membranes whereas corresponding rejection of BOD was observed to be 92% and 86%. A two-dimensional comprehensive model was developed to predict the hydrodynamic profile inside the module. Regression analysis revealed that the simulation results agreed well with experimental data.

Motion control-based seismic retrofit solutions for a R/C school building designed with earlier Technical Standards

The study of two motion control-based seismic retrofit solutions for a low-rise reinforced concrete school building is presented in this paper. The building was assumed as a benchmark structure for a Research Project financed by the Italian Department of Civil Protection, and is representative of several similar public edifices designed with earlier Technical Standards editions, in Italy as well as in other earthquake-prone European countries. The two solutions refer to the alternative earthquake protection strategies based on the concepts of supplemental damping and seismic isolation, respectively. Namely, they consist in the installation of: (1) a dissipative bracing system incorporating pressurized fluid viscous spring-dampers; and (2) a base isolation system including double friction pendulum sliding bearings. The structural characteristics of the building, and a synthesis of the investigation campaigns developed on it, are initially presented. The mechanical parameters, dimensions, locations and installation details of the constituting elements of the two protective systems are then illustrated, along with the performance assessment analyses carried out in original and rehabilitated conditions according to a full non-linear dynamic approach. The results of the analyses show a remarkable enhancement of the seismic response capacities of the structure for both retrofit hypotheses. This allows reaching the mutual high performance levels postulated in the two rehabilitation designs with remarkably lower costs and architectural intrusion as compared to traditional rehabilitation interventions designed for the same objectives.

A viable base isolation strategy for the advanced seismic retrofit of an R/C building

A base isolation seismic retrofit solution for a reinforced concrete school building, designed with earlier Technical Standards, is presented in this paper. The structural characteristics of the building are initially discussed. The mechanical parameters and installation details of the isolation system, incorporating double friction pendulum sliding bearings as protective devices, are then illustrated. The results of the performance assessment analyses carried out in original and rehabilitated conditions show a remarkable enhancement of the seismic response capacities of the structure in base-isolated configuration. The high performance levels postulated in the retrofit design are reached with notably lower costs and architectural intrusion as compared to traditional rehabilitation strategies.

Energy-Saving Analysis in Cellular–WLAN Cooperative Scenarios

This paper addresses scenarios where cellular mobile subscribers implement a cooperative content-sharing service by using short-range radio communications in a wireless local area network (WLAN) and benefit from this situation to reduce the energy consumption. A central entity acts as a coordinator by identifying the data shares to be downloaded by each cooperating user to guarantee fairness and stability of the cooperative downloading process. The intended objective is achieved by carefully modeling the energy consumption on the WLAN radio links and by exploiting the proposed model within the framework of a coalitional game triggered by the coordinator. A performance assessment analysis confirms the expected gains achievable by the cooperative group of users.

Analysis, Design, and Construction of a Base-Isolated Multiple Building Structure

The analysis and design of a multiple residential building, seismically protected by a base isolation system incorporating double friction pendulum sliders as protective devices, are presented in the paper. The building, situated in the suburban area of Florence, is composed of four independent reinforced concrete framed structures, mutually separated by three thermal expansion joints. The plan is L-shaped, with dimensions of about 75 m in the longitudinal direction and about 30 m along the longest side of the transversal direction. These characteristics identify the structure as the largest example of a base-isolated “artificial ground” ever built in Italy. The base isolation solution guarantees lower costs, a much greater performance, and a finer architectural look, as compared to a conventional fixed-base antiseismic design. The characteristics of the building and the isolators, the mechanical properties and the experimental characterization campaign and preliminary sizing carried out on the latter, and the nonlinear time-history design and performance assessment analyses developed on the base isolated building are reported in this paper, along with details about the installation of the isolators and the plants and highlights of the construction works.

Dissipative Bracing-Based Seismic Retrofit of R/C School Buildings

A dissipative bracing system incorporating pressurized fluid viscous spring-dampers has been studied for many years by the authors as an alternative seismic protection strategy for new and existing frame structures. As a concluding stage of this activity, a set of demonstrative case studies was examined to illustrate the enhancement of seismic performance and the economic advantages guaranteed by the system in actual design applications. The paper offers a selection of two among these case studies, both concerning retrofit interventions of reinforced concrete school buildings designed with earlier Seismic Standards editions, representative of a large stock of similar edifices built during the 1970s and earlier 1980s. The following aspects are presented and discussed in detail: the mechanical parameters, layouts and locations selected for the constituting elements of the system; the architectural refurbishment projects developed to properly incorporate the structural interventions and improve the appearance of the buildings; highlights of the installation works completed in one of the two case studies; and a synthesis of the performance assessment analyses in original and rehabilitated conditions, developed according to a full non-linear dynamic approach. The results of the analyses show a remarkable enhancement of the seismic response capacities of both structures. This allows reaching the high performance objectives postulated in the retrofit designs, with much lower costs and architectural intrusion as compared to traditional rehabilitation interventions designed for the same objectives.

Improving the Visibility of Financial Applications Among Signal Processing Researchers[From the Guest Editors

Many problems that arise in the financial industry call for signal processing methods, since financial markets are dependent upon a variety of signals, such as transaction prices and volumes, limit order prices and sizes, quarterly earnings, interest rates, inflation, and credit ratings. Signal processing problems encountered in the design of financial systems come from application areas as diverse as risk management, optimal trade scheduling, portfolio optimization, hedge fund style identification, performance assessment, and impact analysis of business decisions.

Technical and economic assessment of ammonia-based post-combustion CO2 capture

The performance and cost of two ammonia-based post-combustion CO2 capture systems operating at a new supercritical coal-fired power plant were modeled and compared to an amine-based CO2 capture system operating at a similar plant. This assessment showed that for a fixed coal input, the plant derating of a CO2 capture system operating with high ammonia concentrations (HighNH3) was found to be 2 percentage points lower than a plant with the amine-based system. The plant derating of a CO2 capture system operating with low ammonia concentrations (LowNH3) was substantially higher. Preliminary estimates of the revenue requirement of the plants with HighNH3 and LowNH3 systems are $US 117/MWh and $US 148/MWh respectively, compared to $US 119/MWh for a plant with an amine-based system. The results from this performance assessment and preliminary cost analysis suggest that the LowNH3 system will not be competitive and that the HighNH3 system may have a slight energy and cost advantage over the amine system. Furthermore, a preliminary uncertainty analysis explores the critical factors that may affect the performance and cost estimates of these systems, including the potential for slow reaction kinetics to increase absorber costs, and these results are presented.

Performance assessment and reliability analysis of dependable and distributed computing systems based on BDD and recursive merge

System reliability evaluation, sensitivity analysis, failure frequency analysis, importance measures, and optimal design are important issues that have become research topics for distributed dependable computing. Finding all of the Minimal File Spanning Trees (MFST) and avoiding repeatedly computing the redundant MFSTs have been key techniques for evaluating the reliability of a distributed computing system (DCS) in previous works. However, identifying all of the disjointed MFSTs is difficult and time consuming for large-scale networks. Although existing algorithms have been demonstrated to work well on medium-scale networks, they have two inherent drawbacks. First, they do not support efficient manipulation of Boolean algebra. The sum-of-disjoint-products method used by these algorithms is inefficient when dealing with large Boolean functions. Second, the tree-based partitioning algorithm does not merge isomorphic sub-problems, and therefore, redundant computations cannot be avoided. In this paper, we propose a new efficient algorithm for the reliability evaluation of a DCS based on the recursive merge and the binary decision diagram (BDD). Using the BDD substitution method, we can easily apply our algorithm to a network with imperfect nodes. The experimental results show a significant improvement in the execution time compared to previous works.

Structural performance assessment and fatigue analysis of a railway bridge

Increased economic activity in South Africa has put pressure on both rail and road transportation systems. In particular, there is a need to increase loading on the rail systems. The railway network consists of a number of steel bridges approaching the end of their design life. The fitness of these bridges to carry higher loads needs to be assessed. The present paper describes a systematic procedure for the condition assessment of a 100 year old wrought iron railway bridge. Experimental modal analysis techniques were used to calibrate the finite-element model. The calibrated model was used to predict the behaviour of the bridge under proposed loading regimes. Strain measurements were taken at selected locations and were used to assess the fatigue life of the bridge. This work demonstrates the effectiveness of combining experimental modal analysis with actual structural response from live loading for condition assessment and performance prediction.

Dual-Permeability Modeling of Capillary Diversion and Drift Shadow Effects in Unsaturated Fractured Rock

The drift-shadow effect describes capillary diversion of water flow around a drift or cavity in porous or fractured rock, resulting in lower water flux directly beneath the cavity. This paper presents computational simulations of drift-shadow experiments using dual-permeability models, similar to the models used for performance assessment analyses of flow and seepage in unsaturated fractured tuff at Yucca Mountain. Comparisons were made between the simulations and experimental data from small-scale drift-shadow tests. Results showed that the dual-permeability models captured the salient trends and behavior observed in the experiments, but constitutive relations (e.g., fracture capillary-pressure curves) can significantly affect the simulated results. Lower water flux beneath the drift was observed in both the simulations and tests, and fingerlike flow patterns were seen to exist with lower simulated capillary pressures. The dual-permeability models used in this analysis were capable of simulating these processes. However, features such as irregularities along the top of the drift (e.g., from roof collapse) and heterogeneities in the fracture network may reduce the impact of capillary diversion and drift shadow. An evaluation of different meshes showed that at the grid refinement used, a comparison between orthogonal and unstructured meshes did not result in large differences.

Performance assessment and sub-threshold analysis of gate material engineered AlGaN/GaN HEMT for enhanced carrier transport efficiency

The present work explores the features of gate material engineered (GME) AlGaN/GaN high electron mobility transistor (HEMT) for enhanced carrier transport efficiency (CTE) and suppressed short channel effects (SCEs) using 2-D sub-threshold analysis and device simulation. The model accurately predicts the channel potential, electric field and sub-threshold current for the conventional and GME HEMT, taking into account the effect of work function difference of the two metal gates. This is verified by comparing the model results with the ATLAS simulation results. Further, simulation study has been extended to reflect the wide range of benefits exhibited by GME HEMT for its on-state and analog performance. The simulation results demonstrate that the GME HEMT exhibits much higher on current, lower conductance and higher transconductance as compared to the conventional HEMT due to improved CTE and reduced SCEs. This in turn has a direct bearing on the device figure of merits (FOMs) such as intrinsic gain, device efficiency and early voltage. Tuning of GME HEMT in terms of the relative lengths of the two metal gates, their work function difference and barrier layer thickness has further been carried out to enhance the drive current, transconductance and the device FOMs illustrating the superior performance of GME HEMT for future high-performance high-speed switching, digital and analog applications.

Use of groundwater lifetime expectancy for the performance assessment of a deep geologic waste repository: 1. Theory, illustrations, and implications

Long‐term solutions for the disposal of toxic wastes usually involve isolation of the wastes in a deep subsurface geologic environment. In the case of spent nuclear fuel, if radionuclide leakage occurs from the engineered barrier, the geological medium represents the ultimate barrier that is relied upon to ensure safety. Consequently, an evaluation of radionuclide travel times from a repository to the biosphere is critically important in a performance assessment analysis. In this study, we develop a travel time framework based on the concept of groundwater lifetime expectancy as a safety indicator. Lifetime expectancy characterizes the time that radionuclides will spend in the subsurface after their release from the repository and prior to discharging into the biosphere. The probability density function of lifetime expectancy is computed throughout the host rock by solving the backward‐in‐time solute transport adjoint equation subject to a properly posed set of boundary conditions. It can then be used to define optimal repository locations. The risk associated with selected sites can be evaluated by simulating an appropriate contaminant release history. The utility of the method is illustrated by means of analytical and numerical examples, which focus on the effect of fracture networks on the uncertainty of evaluated lifetime expectancy.

Retention of Cs in Boom Clay: Comparison of data from batch sorption tests and diffusion experiments on intact clay cores

For performance assessment analysis of a high-level waste and spent fuel (HLW/SF) disposal in a geological formation, retention data are needed. In most cases, retention data are derived from batch sorption experiments on dispersed systems but the applicability of these data for the real compacted state is still a point of debate. Cesium retention onto Boom Clay was measured by batch sorption tests on dispersed systems and by diffusion experiments on intact clay cores and the sorption parameters obtained from both methods were compared. In a dispersed system, the concentration dependent uptake of cesium onto Boom Clay is described using the generalised 3-sites cation exchange model for illite developed by Bradbury and Baeyens, [Bradbury, M., Baeyens B., 2000. A generalised sorption model for the concentration dependent uptake of cesium by argillaceous rocks. Journal of Contaminant Hydrology 42, 141–163]. In the compacted state, long-term (13.7 years) diffusion experiments resulted in reproducible and robust values for the apparent diffusion coefficient ( D app ). The determination of retardation factors suffered from a large uncertainty making a good comparison troublesome. But the retardation factors obtained from batch sorption data tend to be higher than those obtained by migration experiments. A chemical coupled transport simulation for the Cs migration in Boom Clay based on the ion-exchange model was used for a sensitivity analysis on the effect of increased pore diffusion coefficients and decreasing available sorption sites. This analysis suggests, irrespective of the underlying hypothesis, that in a compacted system not all sorption sites are available. For Cs retention in Boom Clay, conversion of batch sorption data to compacted systems cannot be applied in a straightforward way.