Performance Objectives (performance + objective)

Distribution by Scientific Domains


Selected Abstracts


Treatment of an explosives plume in groundwater using an organic mulch biowall

REMEDIATION, Issue 1 2009
Farrukh Ahmad
A field demonstration of a mulch permeable reactive barrier (PRB), or "biowall," as an in situ treatment technology for explosives in groundwater is summarized. Organic mulch consists of insoluble carbon biopolymers that are enzymatically hydrolyzed during decomposition to release aqueous total organic carbon (TOC). The released TOC is then available for microorganisms to use as an electron donor to transform electrophilic contaminants via reductive pathways. A 100-foot-long and 2-foot-thick mulch biowall was installed at the Pueblo Chemical Army Depot in Colorado to treat a shallow groundwater plume containing hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). To discourage groundwater flow bypassing around and under the biowall in this highly permeable formation, a hydraulic control was installed and the PRB was keyed into the bedrock. Technology performance was monitored using a monitoring well network to establish the development and extent of the downgradient treatment zone. Performance objectives of the field demonstration were: (1) greater than 90 percent removal of RDX across the PRB and the treatment zone; (2) an RDX concentration of less than 0.55 ,g/L in the treatment zone; and (3) cumulative toxic intermediate concentration (nitroso intermediates of RDX, MNX, DNX, and TNX) of less than 20 percent of the upgradient RDX concentration. All performance objectives were met within seven months after installation once the system reached a pseudo-steady state. By this point, a sustained reducing/treatment zone had been created downgradient of the mulch PRB that showed greater than 93 percent RDX removal, RDX concentrations less than 0.55 ,g/L, and no accumulation of toxic intermediates. The mulch biowall implemented during this demonstration was successful at meeting performance objectives while addressing the majority of potential concerns of the technology. © 2009 Wiley Periodicals, Inc. [source]


Predictive control of parabolic PDEs with state and control constraints

INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 16 2006
Stevan Dubljevic
Abstract This work focuses on predictive control of linear parabolic partial differential equations (PDEs) with state and control constraints. Initially, the PDE is written as an infinite-dimensional system in an appropriate Hilbert space. Next, modal decomposition techniques are used to derive a finite-dimensional system that captures the dominant dynamics of the infinite-dimensional system, and express the infinite-dimensional state constraints in terms of the finite-dimensional system state constraints. A number of model predictive control (MPC) formulations, designed on the basis of different finite-dimensional approximations, are then presented and compared. The closed-loop stability properties of the infinite-dimensional system under the low order MPC controller designs are analysed, and sufficient conditions that guarantee stabilization and state constraint satisfaction for the infinite-dimensional system under the reduced order MPC formulations are derived. Other formulations are also presented which differ in the way the evolution of the fast eigenmodes is accounted for in the performance objective and state constraints. The impact of these differences on the ability of the predictive controller to enforce closed-loop stability and state constraints satisfaction in the infinite-dimensional system is analysed. Finally, the MPC formulations are applied through simulations to the problem of stabilizing the spatially-uniform unstable steady-state of a linear parabolic PDE subject to state and control constraints. Copyright © 2006 John Wiley & Sons, Ltd. [source]


Three-dimensional vibration control of high-tech facilities against earthquakes and microvibration using hybrid platform

EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 6 2010
Xiao-Jian Hong
Abstract High-tech equipments engaged in the production of ultra-precision products have very stringent vibration criteria for their functionality in normal operation conditions and their safety during an earthquake. Most previous investigations were based on simplified planar models of building structures, despite the fact that real ground motions and structures are always three-dimensional. This paper hence presents a three-dimensional analytical study of a hybrid platform on which high-tech equipments are mounted for their vibration mitigation. The design methodology of the hybrid platform proposed in this study is based on dual-level performance objectives for high-tech equipments: safety against seismic hazard and functionality against traffic-induced microvibration. The passive devices (represented by springs and viscous dampers) and the active actuators are designed, respectively, to meet vibration criteria corresponding to safety level and functionality level. A prototype three-story building with high-tech equipments installed on the second floor is selected in the case study to evaluate the effectiveness of the hybrid platform. The optimal location of the platform on the second building floor is determined during the design procedure in terms of the minimal H2 cost function of absolute velocity response. The simulation of the coupled actuator-platform-building system subjected to three-dimensional ground motions indicates that the optimally designed hybrid platform can well achieve the dual target performance and effectively mitigate vibration at both ground motion levels. Copyright © 2009 John Wiley & Sons, Ltd. [source]


Probabilistic evaluation of seismic performance of 3-story 3D one- and two-way steel moment-frame structures

EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 5 2008
Hiroyuki Tagawa
Abstract This paper presents the results of a probabilistic evaluation of the seismic performance of 3D steel moment-frame structures. Two types of framing system are considered: one-way frames typical of construction in the United States and two-way frames typical of construction in Japan. For each framing system, four types of beam,column connections are considered: pre-Northridge welded-flange bolted-web, post-Northridge welded-flange welded-web, reduced-beam-section, and bolted-flange-plate connections. A suite of earthquake ground motions is used to compute the annual probability of exceedence (APE) for a series of drift demand levels and for member plastic-rotation capacity. Results are compared for the different framing systems and connection details. It is found that the two-way frames, which have a larger initial stiffness and strength than the one-way frames for the same beam and column volumes, have a smaller APE for small drift demands for which members exhibit no or minimal yielding, but have a larger APE for large drift demands for which members exhibit large plastic rotations. However, the one-way frames, which typically comprise a few seismic frames with large-sized members that have relatively small rotation capacities, may have a larger APE for member failure. The probabilistic approach presented in this study may be used to determine the most appropriate frame configuration to meet an owner's performance objectives. Copyright © 2008 John Wiley & Sons, Ltd. [source]


Performance-based seismic analysis and design of suspension bridges

EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 4-5 2005
Serafim Arzoumanidis
Abstract This paper presents a performance-based seismic analysis and design of a large suspension bridge, the new Tacoma Narrows Parallel Crossing in the State of Washington. The scope of the project included establishment of design criteria, extensive analysis and validation of the design. The analysis was performed using detailed three-dimensional models that included geometric and material non-linearity. The target post-earthquake level of service was verified using stress, deformation and ductility criteria. In the absence of well-established criteria, which relate the structural response of tower shafts to specific levels of performance, capacity analyses were performed to demonstrate that the design fulfills the performance objectives. The seismic analysis and design of this bridge was reviewed throughout the design process. An independent check team also performed separate analysis and validation of the design. Thus, this bridge constitutes an example of a large-scale design project where the performance-based seismic design procedures underwent rigorous assessment. This work demonstrated that the performance-based approach for seismic design is an appropriate way for designing earthquake-resistant structures. Further data that relate the structural response with the performance objectives are necessary. Copyright © 2005 John Wiley & Sons, Ltd. [source]


Worker flexibility and its perceived contribution to performance: The moderating role of task characteristics

HUMAN FACTORS AND ERGONOMICS IN MANUFACTURING & SERVICE INDUSTRIES, Issue 2 2007
Eric Molleman
This study examined the relationship between worker flexibility in team-based work and its perceived contribution to efficiency, work quality, and innovation, and the moderating role of task autonomy, skill utilization, and task monotony. Four-hundred ninety-four employees from 113 teams in 15 organizations completed and returned questionnaires. Skill utilization proved to be positively related to perceived contribution of flexibility to efficiency, work quality, and innovation. Furthermore, skill utilization strengthened the positive relationships between worker flexibility and its perceived contribution to efficiency and work quality and weakened the negative relationship between worker flexibility and its perceived impact on innovation. Task monotony was negatively related to the perceived quality benefits of being flexible. In addition, it weakened the positive relationship between worker flexibility and its perceived contribution to both efficiency and quality and strengthened the negative relationship with the perceived impact of flexibility on innovation. Task autonomy was positively related to the perceived contribution of flexibility to innovation and weakened the negative relationship between worker flexibility and the perceived innovation benefits of being flexible. The authors conclude that skill utilization and lack of monotony are important issues in relation to worker flexibility on all performance objectives that were considered, whereas task autonomy seems especially relevant when innovation is a key issue. © 2007 Wiley Periodicals, Inc. Hum Factors Man 17: 117,135, 2007. [source]


The Influence of Regular Work Systems on Compensation for Contingent Workers

INDUSTRIAL RELATIONS, Issue 4 2003
Article first published online: 16 SEP 200, Brenda A. Lautsch
Using data from a nationally representative survey of U.S. establishments, this article explores how features of regular work influence outcomes for contingent workers. The results show that firms combine regular and contingent work in varied ways: Some managers design contingent work to achieve performance objectives not possible with the regular workforce, whereas managers in other cases create contingent jobs to reinforce the same goals as regular work. In the latter case, contingent workers are more likely to be integrated with regular workers and to receive benefits. Benefit provision for contingent workers is also influenced by traditional internal labor market rules and by spillover effects in which efficiency or regulatory requirements lead benefits to be extended to contingent staff once offered to regular workers. [source]


A contingency approach to reward strategy in the UK not-for-profit sector

INTERNATIONAL JOURNAL OF NONPROFIT & VOLUNTARY SECTOR MARKETING, Issue 4 2000
Anjali Bakhru
The word ,charity' is derived from the Latin word ,caritas', meaning love of other people or beneficence and liberality to those in distress. It is argued, however, that as organisations within the charity or not-for-profit (NFP) sector become more commercial or ,business-like', the greater is the imperative to focus on effectiveness as well as efficiency. In terms of an organisation's reward strategy, it is critical that individual performance is assessed and linked to rewards. The aim of the paper is essentially to examine current approaches to reward strategy in the UK voluntary sector as well as to assess the ,effectiveness' of existing reward strategies, making suggestions as to how a ,best practice' approach could be adopted. Primary data were gathered from organisations within the NFP sector, and it was concluded that the sector needs to question the ,effectiveness' of reward strategies, to link individual performance objectives with its reward strategy, and to move away from pure cost-efficiency considerations to ensure that there is a balance between long-term and short-term objectives. At the same time, a ,best practice' approach for reward strategies within the NFP sector cannot be prescriptive in terms of suggesting ,one best way', but rather a contingency approach is recommended with regard to the selection of the mix of financial and non-financial factors within the reward strategy. Copyright © 2000 Henry Stewart Publications. [source]


Linear, parameter-varying control and its application to a turbofan engine

INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 9 2002
Gary J. BalasArticle first published online: 15 JUL 200
This paper describes application of parameter-dependent control design methods to a turbofan engine. Parameter-dependent systems are linear systems, whose state-space descriptions are known functions of time-varying parameters. The time variation of each of the parameters is not known in advance, but is assumed to be measurable in real-time. Three linear, parameter-varying (LPV) approaches to control design are discussed. The first method is based on linear fractional transformations which relies on the small gain theorem for bounds on performance and robustness. The other methods make use of either a single (SQLF) or parameter-dependent (PDQLF) quadratic Lyapunov function to bound the achievable level of performance. The latter two techniques are used to synthesize controllers for a high-performance turbofan engine. A LPV model of the turbofan engine is constructed from Jacobian linearizations at fixed power codes for control design. The control problem is formulated as a model matching problem in the ,, and LPV framework. The objective is decoupled command response of the closed-loop system to pressure and rotor speed requests. The performance of linear, ,, point designs are compared with the SQLF and PDQLF controllers. Nonlinear simulations indicate that the controller synthesized using the SQLF approach is slightly more conservative than the PDQLF controller. Nonlinear simulations with the SQLF and PDQLF controllers show very robust designs that achieve all desired performance objectives. Copyright © 2002 John Wiley & Sons, Ltd. [source]


Design of full state feedback finite-precision controllers

INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 6 2002
Raffaello D'Andrea
Abstract In this paper, the Generalized L2 Synthesis framework is brought to bear on the problem of control design of full state feedback finite-precision controllers. In particular, we investigate the problem of designing full state feedback controllers that achieve guaranteed H-infinity performance objectives, subject to finite precision constraints on the controller. It is shown that by adopting the Generalized L2 Synthesis framework, the errors in the controller implementation can be captured as full structured uncertainty, and computationally tractable linear matrix inequality techniques used for analysis and synthesis. Copyright © 2002 John Wiley & Sons, Ltd. [source]


Normative decision making with multiattribute performance targets

JOURNAL OF MULTI CRITERIA DECISION ANALYSIS, Issue 3-4 2009
Ali E. Abbas
Abstract Many companies set multiple performance targets for their managers and reward them on meeting a threshold value for each target or goal. Examples of such incentive structures abide in the managerial literature and in organizational settings. We show that this incentive structure, while popular, has two main problems: (i) it can induce managers who try to maximize the probability of meeting their performance targets to make decisions that are not compatible with expected utility maximizing decisions, and (ii) it may lead to trade-offs among the performance objectives that are inconsistent with the corporate value function. In this paper, we propose a method to remedy these two problems, while retaining a target-based incentive scheme. We define a multiattribute target as a deterministic region in the space of multiattribute outcomes that has two properties: (1) the probability that the outcome of a multiattribute lottery lies within the target region is equal to the expected utility of the lottery, and (2) all outcomes within the target region are preferred to all outcomes outside it. These two properties lead to a new quantity; which we call the ,value aspiration equivalent' that leads managers who maximize the probability of meeting their targets to simultaneously maximize the expected utility, and it also induces trade-offs that are consistent with the decision maker's value function. Copyright © 2009 John Wiley & Sons, Ltd. [source]


Multiobjective optimization of semibatch reactive crystallization processes

AICHE JOURNAL, Issue 5 2007
Debasis Sarkar
Abstract The determination of the optimal feed profiles for a reactive crystallizer is an important dynamic optimization problem, as the feed profiles offer a significant control over the quality of the product crystals. Crystallization processes typically have multiple performance objectives and optimization using different objective functions leads to significantly different optimal operating conditions. Therefore, a multiobjective approach is more appropriate for optimization of these processes. The potential for multiobjective optimization approach is demonstrated for semibatch reactive crystallization processes. The multiobjective approach usually gives rise to a set of optimal solutions, largely known as Pareto-optimal solutions. The Pareto-optimal solutions can help the designer visualize the trade-offs between different objectives, and select an appropriate operating condition for the process. A well known multiobjective evolutionary algorithm, the elitist nondominated sorting genetic algorithm, has been adapted to illustrate the potential for the multiobjective optimization approach. © 2007 American Institute of Chemical Engineers AIChE J, 2007 [source]


Options-Based Multi-Objective Evaluation of Product Platforms

NAVAL ENGINEERS JOURNAL, Issue 3 2007
JAVIER P. GONZALEZ-ZUGASTI
A platform is the set of elements and interfaces that are common to a family of products. Design teams must choose among feasible platform concepts upon which a product family could be based, often involving new technologies. Multiple performance objectives need to be considered. A standard approach is to convert the performance outcomes into financial figures, which can then be weighed against the required investments. However, it is not always possible to transform performance outcomes (benefits) into monetary terms, such as in defense or highly technical projects. A multi-objective form of real-options-based platform selection is developed. Systems are compared based on multiple technical and economic goals, incorporating uncertainty by representing the unknown factors during the subsequent development process with probability distributions. The range of uncertain outcomes is integrated into single expected measures of effectiveness, which can then be applied to select the most appropriate platform and set of support product variants. An application to the design of platform-based families of naval high-speed ships is shown. [source]


Designing for performance, part 2: Selecting your performance technologies

PERFORMANCE IMPROVEMENT, Issue 2 2007
Ryan Watkins
Strategic plans and performance objectives define the results to be accomplished, but selecting a suitable set of performance technologies for your organizations requires more than just knowing the intended benefits. The systematic procedures described in the article will guide you through practical processes and valuable tools for identifying potential performance technologies, evaluating alternatives, and developing a system of performance-focused activities that accomplish desired results. [source]


Designing for performance, Part 1: Aligning your HPT decisions from top to bottom

PERFORMANCE IMPROVEMENT, Issue 1 2007
Ryan Watkins
Wanting to improve individual and organizational performance is a worthwhile ambition. Yet your success in accomplishing this relies heavily on the suitable selection, design, and development of performance technologies. Only when capable performance technologies are systematically aligned with the desired results of your organization and its partners will you achieve sustainable performance improvements. In this article, the first of a three-part series, you will find a systematic process for initiating the design of a performance system that will accomplish useful results. From identifying the performance expectations of internal and external partners to justifying the performance objectives you establish as guides for future decision making, the systematic processes described in this article will provide you with the initial tools for successfully selecting an integrated set of performance technologies that have the capacity to accomplish valuable results. [source]


Treatment of an explosives plume in groundwater using an organic mulch biowall

REMEDIATION, Issue 1 2009
Farrukh Ahmad
A field demonstration of a mulch permeable reactive barrier (PRB), or "biowall," as an in situ treatment technology for explosives in groundwater is summarized. Organic mulch consists of insoluble carbon biopolymers that are enzymatically hydrolyzed during decomposition to release aqueous total organic carbon (TOC). The released TOC is then available for microorganisms to use as an electron donor to transform electrophilic contaminants via reductive pathways. A 100-foot-long and 2-foot-thick mulch biowall was installed at the Pueblo Chemical Army Depot in Colorado to treat a shallow groundwater plume containing hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). To discourage groundwater flow bypassing around and under the biowall in this highly permeable formation, a hydraulic control was installed and the PRB was keyed into the bedrock. Technology performance was monitored using a monitoring well network to establish the development and extent of the downgradient treatment zone. Performance objectives of the field demonstration were: (1) greater than 90 percent removal of RDX across the PRB and the treatment zone; (2) an RDX concentration of less than 0.55 ,g/L in the treatment zone; and (3) cumulative toxic intermediate concentration (nitroso intermediates of RDX, MNX, DNX, and TNX) of less than 20 percent of the upgradient RDX concentration. All performance objectives were met within seven months after installation once the system reached a pseudo-steady state. By this point, a sustained reducing/treatment zone had been created downgradient of the mulch PRB that showed greater than 93 percent RDX removal, RDX concentrations less than 0.55 ,g/L, and no accumulation of toxic intermediates. The mulch biowall implemented during this demonstration was successful at meeting performance objectives while addressing the majority of potential concerns of the technology. © 2009 Wiley Periodicals, Inc. [source]