文中将IOCO(Input-Output Conformance)一致性测试理论与着色Petri网(Colored Petri Nets,CPN)进行优势融合,提出一种使用CPN描述测试目的模型并驱动IOCO一致性测试选择的新方法,称为PN4TS方法.PN4TS方法首先定义了面向一致性测试的CPN...文中将IOCO(Input-Output Conformance)一致性测试理论与着色Petri网(Colored Petri Nets,CPN)进行优势融合,提出一种使用CPN描述测试目的模型并驱动IOCO一致性测试选择的新方法,称为PN4TS方法.PN4TS方法首先定义了面向一致性测试的CPN模型(Conformance Testing oriented CPN,CT-CPN),描述软件系统的功能行为;定义了基于CT-CPN描述的PN-IOCO一致性关系;之后,构建CT-CPN描述的测试目的模型,并将该模型与描述软件功能行为的CT-CPN模型执行同步模拟,提出了一种测试目的模型驱动的IOCO一致性测试选择方法,并证明了所生成测试例的可靠性及其对测试目的的覆盖完备性.PN4TS方法以实际测试数据驱动测试例的生成过程,有效保证了经测试目的选择所生成的测试例是切实可执行的.文中使用简单文件传输协议例示了PN4TS方法的应用过程,之后结合数字内容点对点网络分发软件系统的实际测试生成和测试执行实践,证实了PN4TS方法应用于较大规模软件系统的一致性测试应用时具有更好的可用性和可靠性.展开更多
The communication in the physical layer between an interrogator and a tag of a passive Radio Frequency Identification （RFID） system operating between 860-960 MHz is defined by the Gen 2 protocol. The tag can be cons...The communication in the physical layer between an interrogator and a tag of a passive Radio Frequency Identification （RFID） system operating between 860-960 MHz is defined by the Gen 2 protocol. The tag can be considered a remote executing unit or a computer that executes instructions from the Gen 2 protocol. The selection of the parameter and command configuration within the protocol limitations is critical especially if the time available for the memory operations in a passive RFID system is limited. An effort is made to map the operation of the tag not in its states of operation as elaborately explained in the protocol but rather in its elementary format. The research reported in this article identifies all the parameters that affect the dynamic operation of the tag. The operation is further divided into singulation, read and write; identifying the significant parameters in each case. The choices of the different commands that can be adopted to perform identical operations on the tag are analyzed. The elements to consider in selecting the optimum command configuration are described. The impact of the different parameter and command configuration on the singulation, read and write time is calculated and recorded using a tested Gen 2 simulator program.展开更多
In aerodynamics, the laminar or turbulent regime of a boundary layer has a strong influence on friction or heat transfer. In practical applications, it is sometimes necessary to trip the transition to turbulent, and a...In aerodynamics, the laminar or turbulent regime of a boundary layer has a strong influence on friction or heat transfer. In practical applications, it is sometimes necessary to trip the transition to turbulent, and a common way is by use of a roughness element （e.g. a step） on the wall. The present paper is concerned with the numerical im- plementation of such a trip in large-eddy simulations. The study is carried out on a flat-plate boundary layer con- figuration, with Reynolds number Rex=l.3x 106. First, this work brings the opportunity to introduce a practical methodology to assess convergence in large-eddy simulations. Second, concerning the trip implementation, a volume source term is proposed and is shown to yield a smoother and faster transition than a grid step. Moreover, it is easier to implement and more adaptable. Finally, two subgrid-scale models are tested： the WALE model of Nic0ud and Ducros （Flow Turbul. Combust., vol. 62, 1999） and the shear-improved Smagorinsky model of Ldv^que et al. （J. Fluid Mech., vol. 570, 2007）. Both models allow transition, but the former appears to yield a faster transition and a better prediction of friction in the turbulent regime.展开更多
文摘The communication in the physical layer between an interrogator and a tag of a passive Radio Frequency Identification （RFID） system operating between 860-960 MHz is defined by the Gen 2 protocol. The tag can be considered a remote executing unit or a computer that executes instructions from the Gen 2 protocol. The selection of the parameter and command configuration within the protocol limitations is critical especially if the time available for the memory operations in a passive RFID system is limited. An effort is made to map the operation of the tag not in its states of operation as elaborately explained in the protocol but rather in its elementary format. The research reported in this article identifies all the parameters that affect the dynamic operation of the tag. The operation is further divided into singulation, read and write; identifying the significant parameters in each case. The choices of the different commands that can be adopted to perform identical operations on the tag are analyzed. The elements to consider in selecting the optimum command configuration are described. The impact of the different parameter and command configuration on the singulation, read and write time is calculated and recorded using a tested Gen 2 simulator program.
文摘In aerodynamics, the laminar or turbulent regime of a boundary layer has a strong influence on friction or heat transfer. In practical applications, it is sometimes necessary to trip the transition to turbulent, and a common way is by use of a roughness element （e.g. a step） on the wall. The present paper is concerned with the numerical im- plementation of such a trip in large-eddy simulations. The study is carried out on a flat-plate boundary layer con- figuration, with Reynolds number Rex=l.3x 106. First, this work brings the opportunity to introduce a practical methodology to assess convergence in large-eddy simulations. Second, concerning the trip implementation, a volume source term is proposed and is shown to yield a smoother and faster transition than a grid step. Moreover, it is easier to implement and more adaptable. Finally, two subgrid-scale models are tested： the WALE model of Nic0ud and Ducros （Flow Turbul. Combust., vol. 62, 1999） and the shear-improved Smagorinsky model of Ldv^que et al. （J. Fluid Mech., vol. 570, 2007）. Both models allow transition, but the former appears to yield a faster transition and a better prediction of friction in the turbulent regime.
