5,588 research outputs found
Robust Dynamic Selection of Tested Modules in Software Testing for Maximizing Delivered Reliability
Software testing is aimed to improve the delivered reliability of the users.
Delivered reliability is the reliability of using the software after it is
delivered to the users. Usually the software consists of many modules. Thus,
the delivered reliability is dependent on the operational profile which
specifies how the users will use these modules as well as the defect number
remaining in each module. Therefore, a good testing policy should take the
operational profile into account and dynamically select tested modules
according to the current state of the software during the testing process. This
paper discusses how to dynamically select tested modules in order to maximize
delivered reliability by formulating the selection problem as a dynamic
programming problem. As the testing process is performed only once, risk must
be considered during the testing process, which is described by the tester's
utility function in this paper. Besides, since usually the tester has no
accurate estimate of the operational profile, by employing robust optimization
technique, we analysis the selection problem in the worst case, given the
uncertainty set of operational profile. By numerical examples, we show the
necessity of maximizing delivered reliability directly and using robust
optimization technique when the tester has no clear idea of the operational
profile. Moreover, it is shown that the risk averse behavior of the tester has
a major influence on the delivered reliability.Comment: 19 pages, 4 figure
Generation of cluster states
We propose two schemes for the generation of the cluster states. One is based
on cavity quantum electrodynamics (QED) techniques. The scheme only requires
resonant interactions between two atoms and a single-mode cavity. The
interaction time is very short, which is important in view of decoherence.
Furthermore, we also discuss the cavity decay and atomic spontaneous emission
case. The other is based on atomic ensembles. The scheme has inherent fault
tolerance function and is robust to realistic noise and imperfections. All the
facilities used in our schemes are well within the current technology.Comment: Complete rewite version, adding the main results of quant-ph/0511045.
7 pages and 3 figure
Thermomass Theory: A Mechanical Pathway to Analyze Anomalous Heat Conduction in Nanomaterials
The synthesis and measurements of nanomaterials have yielded significant advances in the past decades. In the area of thermal conduction, the nanomaterials exhibit anomalous behavior such as size-dependent thermal conductivity, thermal rectification, and ultra-high thermoelectric properties. The theoretical understanding and modeling on these behaviors are much desired. In this chapter, we study the thermal conduction in nanomaterials through the thermomass theory, which models the heat transfer from a fluid mechanics viewpoint. The control equations of the equivalent mass of the thermal energy are formulated following the continuum mechanics principles, which give the general heat conduction law. It incorporates nonlinear effects such as spatial acceleration and boundary resistance, which can overcome the drawbacks of the traditional Fourier’s law in nanoscale systems. By the thermomass theory, we successfully model the size-dependent effective thermal conductivity in nanosystems. Furthermore, the thermal rectification as well as the thermoelectric enhancement in nanosystems is also discussed with the present framework
Environmental performance rating and disclosure - China's green-watch program
This paper describes a new incentive-based pollution control program in China in which the environmental performance of firms is rated and reported to the public. Firms are rated from best to worst using five colors-green, blue, yellow, red, and black-and the ratings are disseminated to the public through the media. The impact has been substantial, suggesting that public disclosure provides a significant incentive for firms to improve their environmental performance. The paper focuses on the experience of the first two disclosure programs, in Zhenjiang, Jiangsu Province and Hohhot, Inner Mongolia. Successful implementation of these programs at two very different levels of economic and institutional development suggests that public disclosure should be feasible in most of China. The Zhenjiang and Hohhot experiences have also shown that performance disclosure can significantly reduce pollution, even in settings where environmental nongovernmental organizations are not very active and there is no formal channel for public participation in environmental regulation.Environmental Economics&Policies,Public Health Promotion,Decentralization,Water and Industry,Health Monitoring&Evaluation,Environmental Economics&Policies,Water and Industry,Health Monitoring&Evaluation,National Governance,Health Economics&Finance
Energetic macroscopic representation control method for a hybrid-source energy system including wind, hydrogen, and fuel cell
This paper proposes a new control method for a hybrid energy system. A wind turbine, a hydrogen energy storage system, and a proton exchange membrane fuel cell are utilized in the system to balance the load and supply. The system is modeled in MATLAB/Simulink and is controlled by an improved energetic macroscopic representation (EMR) method in order to match the load profile with wind power. The simulation and test results have proved that (1) the proposed system is effective to meet the varying load demand with fluctuating wind power inputs, (2) the hybrid energy storage system can improve the stability and fault-ride-through performance of the system, and (3) the dynamic response of the proposed system is satisfactory to operate with wind turbines, energy storage, and fuel cells under EMR control
The universal "heartbeat" oscillations in black hole systems accross the mass-scale
The hyperluminous X-ray source (HLX-1, the peak X-ray luminosity ) near the spiral galaxy ESO 243-49 is possibly the best
candidate for intermediate mass black hole (IMBH), which underwent recurrent
outbursts with a period of days. The physical reason for this
quasi-periodic variability is still unclear. We explore the possibility of
radiation-pressure instability in accretion disk by modeling the light curve of
HLX-1, and find that it can roughly reproduce the duration, period and
amplitude of the recurrent outbursts HLX-1 with an IMBH of ~10^5Msun. Our
result provides a possible mechanism to explain the recurrent outbursts in
HLX-1. We further find a universal correlation between the outburst duration
and the bolometric luminosity for the BH sources with a very broad mass range
(e.g., X-ray binaries, XRBs, HLX-1 and active galactic nuclei, AGNs), which is
roughly consistent with the prediction of radiation-pressure instability of the
accretion disk. These results imply that "heartbeat" oscillations triggered by
radiation-pressure instability may appears in different-scale BH systems.Comment: ApJ in press; 15 pages, 5 Figure
Usage of Rapid Prototyping Technique in Customized Craniomaxillofacial Bone Tissue Engineering Scaffold
LOPINGIAN (LATE PERMIAN) BRACHIOPOD FAUNAS FROM THE QUBUERGA FORMATION AT TULONG AND KUJIANLA IN THE MT. EVEREST AREA OF SOUTHERN TIBET, CHINA
Permian strata containing abundant brachiopods are well developed in the Himalaya Tethys Zone. However, relatively few has been systematically described due to the difficult working condition for collecting. In this paper, we describe the brachiopods from the Qubuerga Formation at the Tulong and Kujianla sections in southern Tibet. The brachiopod faunas consist of 15 species belonging to 11 genera. Among the identified 15 species, Retimarginfera xizangensis, Costiferina indica, Fusispirifer semiplicatus, Spiriferella sinica, Biplatyconcha grandis and Neospirifer (Quadrospina) tibetensis are very common in the equivalents of the Himalaya Tethys Zone including the Selong Group at the Selong Xishan and Qubu sections in southern Tibet, the Senja Formation in northwest Nepal, the Zewan Formation in Kashmir, and the upper part of the Wargal Formation and the Chhidru Formation in the Salt Range, Pakistan. They are all comparable and can be assigned to the Wuchiapingian- early Changhsingian. Since the brachiopods from the Qubuerga Formation at Tulong and Kujianla are all composed of typical Gondwanan, bipolar or cosmopolitan elements, it is conclusive that the Himalaya Tethys Zone in the northern margin of the Indian Plate was still situated at southern high-latitudes under cold palaeoclimatic conditions during most of the Lopingian. The faunal succession at Tulong also recorded a rapid warming at the very end of the Changhsingian in view of the fact that the typical cold-water Lopingian brachiopod, gastropod and bivalve faunas were dramatically replaced by extremely abundant conodonts Clarkina in the basal part of the dolostone unit of the Tulong Formation. This end-Changhsingian warming is comparable with that recorded throughout the Permian-Triassic boundary interval at Selong, Qubu in southern Tibet, the Salt Range, Pakistan and the sections in Kashmir as well as South China
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