This paper describes a data transmission method using a cyclic redundancy check and inaudible frequencies.The proposed method uses inaudible high frequencies from 18 k Hz to 22 k Hz generated via the inner speaker of ...This paper describes a data transmission method using a cyclic redundancy check and inaudible frequencies.The proposed method uses inaudible high frequencies from 18 k Hz to 22 k Hz generated via the inner speaker of smart devices.Using the proposed method,the performance is evaluated by conducting data transmission tests between a smart book and smart phone.The test results confirm that the proposed method can send 32 bits of data in an average of 235 ms,the transmission success rate reaches 99.47%,and the error detection rate of the cyclic redundancy check is0.53%.展开更多
High reliability is the key to performance of electrical control equipment. PLC combines computer technology, automatic control technology and communication technology and becomes widely used for automation of industr...High reliability is the key to performance of electrical control equipment. PLC combines computer technology, automatic control technology and communication technology and becomes widely used for automation of industrial processes. Some requirements of complex PLC systems cannot be satisfied by the traditional verification methods. In this paper, an efficient method for the PLC systems modeling and verification is proposed. To ensure the high-speed property of PLC, we proposed a technique of “Time interval model” and “notice-waiting”. It could reduce the state space and make it possible to verify some complex PLC systems. Also, the conversion from the built PLC model to the Promela language is obtained and a tool PLC-Checker for modeling and checking PLC systems are designed. Using PLC-Checker to check a classical PLC example, a counter-example is found. Although the probability of this logic error occurs very small, it could result in system crash fatally.展开更多
The parallelism of saw guide motion locus against the blade is one of the main iterns in the testing of the geometric precision of the whole woodworking band saxving-machine. It reflects the making and mounting precis...The parallelism of saw guide motion locus against the blade is one of the main iterns in the testing of the geometric precision of the whole woodworking band saxving-machine. It reflects the making and mounting precisions of the sawguide device,having a direct effect on the working performance. the saw timber quality. and the safety (nature) of the woodworking band sawing-machine, so it is of great importance in the testing process of the band sawing-machine assembly and their going out of the plant.展开更多
The method of characteristic(MOC) was adopted to analyze the check valve-induced water hammer behaviors for a Parallel Pumps Feedwater System(PPFS) during the alternate startup process.The motion of check valve disc w...The method of characteristic(MOC) was adopted to analyze the check valve-induced water hammer behaviors for a Parallel Pumps Feedwater System(PPFS) during the alternate startup process.The motion of check valve disc was simulated using inertial valve model.Transient parameters including the pressure oscillation,local flow velocity and slamming of the check valve disc etc.have been obtained.The results showed that severe slamming between the valve disc and valve seat occurred during the alternate startup of parallel pumps.The induced maximum pressure vibration amplitude is up to 5.0 MPa.The scheme of appending a damping torque to slow down the check valve closing speed was also performed to mitigate of water hammer.It has been numerically approved to be an effective approach.展开更多
基金supported by Ministry of Educationunder Basic Science Research Program under Grant No.NRF-2013R1A1A2061478
文摘This paper describes a data transmission method using a cyclic redundancy check and inaudible frequencies.The proposed method uses inaudible high frequencies from 18 k Hz to 22 k Hz generated via the inner speaker of smart devices.Using the proposed method,the performance is evaluated by conducting data transmission tests between a smart book and smart phone.The test results confirm that the proposed method can send 32 bits of data in an average of 235 ms,the transmission success rate reaches 99.47%,and the error detection rate of the cyclic redundancy check is0.53%.
文摘High reliability is the key to performance of electrical control equipment. PLC combines computer technology, automatic control technology and communication technology and becomes widely used for automation of industrial processes. Some requirements of complex PLC systems cannot be satisfied by the traditional verification methods. In this paper, an efficient method for the PLC systems modeling and verification is proposed. To ensure the high-speed property of PLC, we proposed a technique of “Time interval model” and “notice-waiting”. It could reduce the state space and make it possible to verify some complex PLC systems. Also, the conversion from the built PLC model to the Promela language is obtained and a tool PLC-Checker for modeling and checking PLC systems are designed. Using PLC-Checker to check a classical PLC example, a counter-example is found. Although the probability of this logic error occurs very small, it could result in system crash fatally.
文摘The parallelism of saw guide motion locus against the blade is one of the main iterns in the testing of the geometric precision of the whole woodworking band saxving-machine. It reflects the making and mounting precisions of the sawguide device,having a direct effect on the working performance. the saw timber quality. and the safety (nature) of the woodworking band sawing-machine, so it is of great importance in the testing process of the band sawing-machine assembly and their going out of the plant.
基金Supported by the national key laboratory on Bubble Physics and Natural Circulation (BNPC)the Program for New Century Excellent Talents in University (NCET-06-0837)
文摘The method of characteristic(MOC) was adopted to analyze the check valve-induced water hammer behaviors for a Parallel Pumps Feedwater System(PPFS) during the alternate startup process.The motion of check valve disc was simulated using inertial valve model.Transient parameters including the pressure oscillation,local flow velocity and slamming of the check valve disc etc.have been obtained.The results showed that severe slamming between the valve disc and valve seat occurred during the alternate startup of parallel pumps.The induced maximum pressure vibration amplitude is up to 5.0 MPa.The scheme of appending a damping torque to slow down the check valve closing speed was also performed to mitigate of water hammer.It has been numerically approved to be an effective approach.
