| 1. |
- Jin, Ruiqiu, et al.
(författare)
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Numerical investigation of wind-driven natural ventilation performance in a multi-storey hospital by coupling indoor and outdoor airflow
- 2016
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Ingår i: Indoor + Built Environment. - 1420-326X .- 1423-0070. ; 25:8, s. 1226-1247
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Tidskriftsartikel (refereegranskat)abstract
- This study employed two ventilation indexes: local mean age of air and air change rate per hour, to investigate wind-induced natural ventilation of 260 wards of a multi-storey hospital building in suburb of Guangzhou using computational fluid dynamics simulations. Using the surface-grid extrusion technique, high-quality hexahedral grid cells were generated for the coupled outdoor and indoor airflow field. Turbulence was solved by the renormalisation group k-model validated against experimental data with grid independence studies. Homogeneous tracer gas emission was adopted to predict room age of air. The air change rate of cross ventilation and single-sided ventilation can reach 30-160 h-1 and 0.5-7 h-1, respectively. Due to different locations of room openings on the balconies, natural ventilation of a room can be greatly better than its neighbouring room. The wind-induced cross ventilation highly depends on the distance from the room opening to the stagnation point and on the resulting pressure distribution on the target building surface. Furthermore, it is significantly influenced by the upstream buildings, the bent shape of the target building, and the prevailing wind directions. The coupled computational fluid dynamics methodologies with integrated ventilation indexes are useful for assessing the natural ventilation performance in other complex built environments.
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| 2. |
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| 3. |
- Dong, X., et al.
(författare)
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Study on household metering and temperature control in central air-conditioning
- 2010
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Ingår i: Proceedings of the 2010 5th IEEE Conference on Industrial Electronics and Applications, ICIEA 2010. - 9781424450466 ; , s. 931-935
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Konferensbidrag (refereegranskat)abstract
- This paper studies the Frequency Temperature Control mechanism and cold (heat) metering algorithm about central air-conditioning terminal installations. The temperature control and household metering management system for central air-conditioning terminal machine are developed. The system hardware, software design programs and key technologies are expatiated. The terminal machine is integrated with PIC microcontroller, user data acquisition, transmission and control. Delphi language is used in the accounting management system of the host computer. The results show that, the system is no need of new wire, the high performance-price ratio, easy assembly, stable operation and reasonable charge. It is of great significance to adopt the heat and cold metering for the energy conservation, environmental protection and property management. At the same time, it provides the property management with a new technology and channels for the modern intelligent building. © 2010 IEEE.
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| 4. |
- Liu, Yu, et al.
(författare)
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A New Framework and Application of Software Reliability Estimation Based on Fault Detection and Correction Processes
- 2015
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Ingår i: Proceedings. - : IEEE conference proceedings. - 9781467379892 ; , s. 65-74
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Konferensbidrag (refereegranskat)abstract
- Software reliability growth modeling plays an important role in software reliability evaluation. To incorporate more information and provide more accurate analysis, modeling software fault detection and correction processes has attracted widespread research attention recently. However, the assumption of the stochastic fault correction time delay brings more difficulties in modeling and estimating the parameters. In practice, other than the grouped fault data, software test records often include some more detailed information, such as the rough time when one fault is detected or corrected. Such semi-grouped dataset contains more information about fault removal processes than commonly used grouped dataset. Using the semi-grouped datasets can improve the accuracy of time delayed models. In this paper, a fault removal modelling framework for software reliability with semi-grouped data is studied and extended into multi-released software. Also, the corresponding parameter estimation is carried out with Maximum Likelihood estimation method. One test dataset with three releases from a practical software project is applied with the proposed framework, which shows satisfactory performance with the results.
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| 5. |
- Yang, Jianfeng, et al.
(författare)
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Modeling and analysis of reliability of multi-release open source software incorporating both fault detection and correction processes
- 2016
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Ingår i: Journal of Systems and Software. - : Elsevier BV. - 0164-1212 .- 1873-1228. ; 115, s. 102-110
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Tidskriftsartikel (refereegranskat)abstract
- Large software systems require regular upgrading that tries to correct the reported faults in previous versions and add some functions to meet new requirements. It is thus necessary to investigate changes in reliability in the face of ongoing releases. However, the current modeling frameworks mostly rely on the idealized assumption that all faults will be removed instantaneously and perfectly. In this paper, the failure processes in testing multi-release software are investigated by taking into consideration the delays in fault repair time based on a proposed time delay model. The model is validated on real test datasets from the software that has been released three times with new features. A comprehensive analysis of optimal release times based on cost-efficiency is also provided, which could help project managers to determine the best time to release the software.
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| 6. |
- Zhao, B., et al.
(författare)
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A NHPP-based reliability model of wireless sensor networks
- 2014
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Ingår i: Applied Mechanics and Materials. - 9783038351764 ; , s. 877-882
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Konferensbidrag (refereegranskat)abstract
- As the Wireless Sensor Networks(WSNs) are widely applied to various fields recent years, the quality of WSN has been increasingly concerned. Since reliability is the most important factor of quality, how to evaluate reliability of WSN through failure counting is our main subject. In this paper, we try to utilize NHPP theorem in the failure process of WSN and propose a reliability model based on NHPP. And also, the model validation is conducted by simulation.
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| 7. |
- Zhao, B., et al.
(författare)
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An additive NHPP-Based reliability model of wireless sensor networks
- 2014
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Ingår i: Applied Mechanics and Materials. - 9783038351948 ; , s. 3206-3212
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Konferensbidrag (refereegranskat)abstract
- As the Wireless Sensor Networks(WSNs) are widely implemented in various fields recent years, the quality of WSNs has been increasingly concerned. WSNs can usually be divided into sub-nets, which assumed to work or fail independently. Through the failure data of those sub-nets, the additive NHPP model for reliability evaluation is composed, and then the maximum likelihood estimation is applied to estimate the unknown parameters in the model. Finally, the simulation shows that the additive NHPP model is better than general NHPP model under certain circumstances.
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| 8. |
- Zhao, B., et al.
(författare)
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Wireless sensor network reliability modelling based on masked data
- 2015
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Ingår i: International Journal of Sensor Networks (IJSNet). - 1748-1279 .- 1748-1287. ; 17:4, s. 217-223
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Tidskriftsartikel (refereegranskat)abstract
- This paper studies the reliability modelling of wireless sensor networks (WSNs) with the masked data that are often observed in practice. The masked data are the system failure data when exact subsystems or components causing system failures cannot be identified. When the masked data are observed, however, it is difficult to estimate the WSN reliability since the failure processes of the subnets cannot be decomposed into simple subsystem processes. In this paper, an additive non-homogeneous poisson process (NHPP) model is proposed to describe the failure process of the WSN with subnets. The maximum likelihood estimation (MLE) procedure is developed to estimate the parameters in the proposed model. By applying the given procedure, the WSN reliability estimate can be relatively easy to obtain. A numerical example based on simulation data with random masking is also provided to illustrate the applicability of the methodology.
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