Advanced Materials Research Vol. 933

Abstract: Ground source heat pump (GSHP) systems exchange heat with the ground, often through a closed-loop, vertical, borehole heat exchanger (BHE). The performance of the BHE depends on the thermal properties of the ground formation, as well as soil or backfill in the borehole. The design and economic probability of GSHP systems need the thermal conductivity of geological structure and thermal resistance of BHE. Thermal response test (TRT) method allows the in-situ determination of the thermal conductivity (λ) of the ground formation in the vicinity of a BHE, as well as the effective thermal resistance (R_b) of this latter. Thermal properties measured in laboratory experiments do not comply with data of in-situ conditions. The present article describes the results of thermal properties of the BHE whose depth is 100m in Yancheng City, Jiangsu Province, China. As shown in these results, λ and R_b of borehole are determined as 1.84(W·m^-1·K^-1) and 0.121 (m·K·W^-1) respectively.

Abstract: Recently, the threat of hardware Trojans has garnered attention. Hardware Trojans are malicious circuits that are incorporated into large-scale integrations (LSIs) during the manufacturing process. When predetermined conditions specified by an attacker are satisfied, the hardware Trojan is triggered and performs subversive activities without the LSI users even being aware of these activities. In previous studies, a hardware Trojan was incorporated into a cryptographic circuit to estimate confidential information. However, Trojan triggers have seldom been studied. The present study develops several new Trojan triggers and each of them is embedded in a field-programmable gate array (FPGA). Subsequently, the ease of detection of each trigger is verified from the standpoint of area.

Abstract: In this paper, the study on response of a broadband light source for an optical fiber sensor (OFS) based on surface plasmon resonance (SPR) technology is presented. The OFS is made of a multimode optical fiber which cladding was removed and coated with two layers of metal films. As a broadband light source is launched into the OFS at a suitable incident angle, we can obtain the intensity at the output of the optical fiber sensor. With the structure, the refractive index detection can be made by the SPR spectra that are obtained by an Optical Spectrum Analyzer (OSA). The OFS could be valuable for chemical, biological and biochemical sensing, etc. It has some advantages, such as, high resolution and stability, small size and real-time measurement.

Abstract: The once-through boiler is widely used in high capacity unit currently, however its heat storage capacity is small, and the unit’s response lags during primary frequency regulation. These all lead to the limited frequency regulation ability. For the purpose of studying the primary frequency regulation optimized control strategy, this paper established a primary frequency regulation characteristic simulation platform based on stimulative simulation system. Using this platform, it proposed an improved program for once-through boiler’s primary frequency regulation control strategy. It’s supposed to cover the insufficient heat storage capacity of the boiler by introducing the differential feed forward signal of the fuel supply and water flow. The simulation result shows that the proposed control scheme effectively improves the speed of primary frequency regulation. This platform provides a reliable basis for once-through boiler’s primary frequency regulation control strategy, and also has a certain guiding significance for further study.

Abstract: This paper shows the superiority of computer simulation technology based on negative feedback amplifier performance analysis by virtual electronic workbench (EWB) simulation technology.

Abstract: Power semiconductor device and its control circuit of photovoltaic grid-connected inverter is the weakest part in the photovoltaic generation system. Fault feature extraction is the key to the inverter fault diagnosis. Output voltage of inverter is the most sensitive characteristic quantity which can reflect its working status directly. The single transistor open fault diagnosis of photovoltaic grid-connected inverter can be achieved by extracting the output voltage frequency spectrum with the help of windowed STFT. The simulation results demonstrate the effectiveness of the method.

Abstract: The photovoltaic grid-connected inverter is the most important device of photovoltaic generation which is a widely adopted application of solar energy. Its control strategy determines the working status and performance of the photovoltaic generation system. Repetitive control strategy of the photovoltaic grid-connected inverter is analyzed in this paper. The method based on repetitive control and pole assignment is also presented to solve the one-cycle-lag disadvantage of repetitive control, and the simulation model in Matlab/Simulink is established. The simulation results show that the dynamic performance of grid-connected inverter is improved and the waveform deviation rate is reduced effectively with the help of pole assignment.

Abstract: CAN bus was widely used in embedded system development, but most embedded processors without CAN bus controller, need to extend external CAN bus interface through external bus. In order to send and receive the CAN bus data by S3C2440 chip, interface function of S3C2440 was extended by MCP2515 chip in the paper, which was used the SPI interface to extend CAN bus interface. The design of CAN bus hardware interface was described in the paper. The design of CAN device drive program on the embedded Linux operating system was specified in detail.

Abstract: Basic spectrum of categorized hub according to its form is obtained based on search of radical method. Various level codes arise with increasing number of hub samples which belong to basic spectrum subcodes. Transitional form can be created by computerized continuous deformation technique, according to which new codes are generated automatically, and then the codes auto differentiation can be realized. By this way, automatic adjustment, richness and perfectness of the basic spectrum can be achieved, and the efficiency and initiative of categorization can also be improved.

Abstract: The influence of evolutionary power spectrums randomness on synthesized acceleration time history is not considered in the existing time history synthesis methods. In this paper, the calculation methods of evolutionary power spectrums randomness are discussed. The influence of evolutionary power spectrums randomness on synthesized acceleration time history in shape and characteristic parameters are analyzed. The Sensitivity of the effect on shape and characteristic parameters of synthesized acceleration time history by the evolutionary power spectrum modeling parameters randomness are also compared. It shows that, the characteristic of evolutionary power spectrums randomness has little impact on the shape, arrive time of peek value and duration of synthesized time history, but the effect on the ground motion peek acceleration, effective peak acceleration and energy are notable. Characteristic parameters of time history great affect by amplitude of super-randomness characters. When the amplitudes increase from 0.05 to 0.20, the maximum increase of PGA, EPA and E in horizontal component is 10.0%, 15.0% and 19.0%, and the vertical component is 11.6%, 10.8% and 19.0%. So, I suggest that taking the consideration of randomness in synthesis acceleration time history and limiting the amplitude in 0.05 to decrease the error from omitting the effect of randomness, and not bring in randomness which could lead to distortion in calculation.