Papers by Keyword: PCB

Abstract: The electronics package in a spacecraft is subjected to a variety of dynamic loads during launch phase and suitable thermal environment for the mission life. The dynamic and thermal analyses performed for a structurally reconfigured electronics package. Two different simulation models are developed to carry out the analyses. This paper discusses in two parts, in part-1, the vibration responses are determined at various critical locations, including on the Printed Circuit Board (PCB) for the vibration loads specified by launch vehicle using Finite Element Analysis (FEA). The mechanical properties of PCB are determined from the test specimens, which are then incorporated in the finite element model. In part-2, the steady-state temperature distributions on the components and on the PCB are determined, to check the effectiveness of heat transfer path from the components to the base of the package and to verify the predicted values are within the acceptable temperature limits specified. The predicted temperature values are then compared with on-orbit observations.

Abstract: With the circuit fabrication technology continues toward high-speed, high-density, low-power direction, modern circuit design techniques have changed radically. The speed improvement of digital system means rise and fall time of signals as short as possible, the improvement of frequency and edge rates will bring a series of high-speed design problems, these problems bring great challenges to the system hardware design, the correct design from logical point of view, if there is improper in the actual PCB design will lead to failure of the entire design. EMI radiation of PCB is analyzed, EMC simulation of PCB and optimizing improved are finished. The PCB electromagnetic compatibility is analyzed by using Protel 99SE and Ansoft Designer 2.2 software, and simulation result indicates optimizing design is correct and effective.

Abstract: This system consists of a pressure silicon sensor, calibration module and wireless module. The pressure sensor used in this work is a piezoresistive silicon sensor that developed by Technical University Berlin. After calibration of the sensors output signals, the XBee-chip was used for wireless transmission. The three components with peripheral circuits and batteries were integrated in a 50mm × 50mm PCB. The system was then tested in a climate chamber at different temperatures and pressures. Programs for signal receiving and processing were developed in Matlab-environment. The experimental results show that this system works well for the short range (15m indoor).

Abstract: In order to know about the variation of PAHs, PCBs and OCPs of sludge in landfill, discover the factors influencing the contents of PAHs, PCBs, OCPs and provide the scientific basis for the agriculture reuse of aged-sludge, the variation of PAHs, PCBs, OCPs contents and influencing factors in sludge landfill were studied in this paper. PAHs concentration of different landfill periods rang from 6.645 to 10.008 mg·kg^-1 and show an increasing tendency with the increase of landfill duration. PAHs are mainly composed of more than four benzene-based compounds, and less than three benzene rings compounds contents of PAHs are relatively low. PCBs concentrations rang from 15.655 to 25.569 μg·kg^-1 and present a decreasing trend with the landfill time, which far less than the standard of 0.2 mg·kg^-1. PCBs at the beginning of the landfill are mainly composed of the 3-Cl and 5-Cl compounds. In the late of the landfill, 2-Cl compounds increase significantly. The range of OCPs concentration is 1.78~2.37 μg·kg^-1. The main factors affecting the PAHs, PCBs and OCPs contents are microbial degradation and transformation. Analysis of the pollutants sources indicate that PAHs in sludge are mainly derived from the waste water of refinery, coking plant, gasworks, smelt plant and pitch plant. Chemical industry, timber process and electricity industry are the main sources of PCBs and OCPs in sludge.

Abstract: A real PCBs contaminated soil was heated at 500°C using pure nitrogen as carrier gas under different flow rate to investigate the influence of carrier gas flow rate on the thermal desorption process. After 1 hour thermal treatment, the residual PCBs in soil decreased and the removal efficiency (RE) of PCBs is up to 95.1%. The distributions of PCBs in soil under different flow rate were identical. The World Health Organization toxic equivalency quantity (WHO TEQ) of PCBs in soil got its lowest value at 400Nml/min. Tetra-and higher chlorinated PCBs desorbed to carrier gas increased with increased flow rate, while the total amount of PCBs, Tri-and lower chlorinated PCBs first increased then decreased. The distributions of PCBs in carrier gas became more closely to the raw soil with increased flow rate. The TEQ of PCBs in carrier gas increased with increased flow rate. Increased flow rate enhanced the mass transfer of PCBs in the soil but shortened the preheating time of carrier gas and the retention time of carries gas, weakening the mass transfer and degradation process in gas phase. The RE of WHO TEQ of PCDDs in treated soil decreased from 86.7% to 83.2% with increased flow rate while the RE of WHO TEQ of PCDFs decreased from 85.4% to 70.0%. After thermal treatment process, the total amount of PCDD/Fs TEQ in soil and carrier gas increase from 43.8% to 18.6% times of that in raw soil. Considering removal efficiency of PCBs and PCDD/Fs and generation of PCDD/Fs in soil and gas phase, an optimized flow rate should be set at about 400Nml/min.

Abstract: Plasma is ionized gas-like substance, comprised by the e-deprived atoms and electron-positron. Plasma possess the characteristics of high energy, high thermal capacity, fast response and electric conversion efficiency, which shows unique advantages and good prospects for the effective disposal of POPs wastes. This paper introduced the basic principle and mechanism of plasma arc technology as a non-combustion technology; reviewed the development of application of plasma technology in the processing of HFC23, organic fluoride industrial waste, phenyl chlorosilane residue, medical waste, printed circuit board, chemical weapons and other hazardous wastes; analyzed the major technical and economic advantages and disadvantages for the plasma technologies in the POPs waste treatment; And corresponding comments and suggestions were proposed to promote the application of plasma technology for POPs waste disposal in China.

Abstract: Small and efficient energy harvesters, as a renewable power supply, draw lots of attention in the last few years. This paper presents a planar rotary electromagnetic generator with copper coils fabricated by using printed circuit board (PCB) as inductance and Nd-Fe-B magnets as magnetic element. Coils are fabricated on PCB, which is presumably cost-effective and promising methods. 28-pole Nd-Fe-B magnets with outer diameter of 50 mm and thickness of 2 mm was sintered and magnetized, which can provide magnetic field of 1.44 Tesla. This harvester consists of planar multilayer with multi-pole coils and multi-pole permanent magnet, and the volume of this harvester is about 50x50x2.5 mm³. Finite element analysis is used to design energy harvesting system, and simulation model of the energy harvester is established. In order to verify the simulation, experiment data are compared with simulation result. The PCB energy harvester prototype can generate induced voltage 0.61 V and 13.29mW output power at rotary speed of 4,000 rpm.

Abstract: In the processing of PCB (Printed Circuit Board) defect inspection with reference comparison method, the very critical aspect is to make the image to be inspected and the reference standard PCB image accurate registration . Image registration has many ways, according to the characteristics of PCB, a new image registration method based on Mark hole center feature extraction was presented, also this method is carried out relevant experimental verification.

Abstract: s. To explore the PCB pollution characteristics in the airborne particulate matter, seven indicative polychlorinated biphenyls (PCBs) in atmospheric PM₁₀ were determined weekly in Jinan, China. PCB concentrations, profiles, temporal distribution pattern and the correlations between Σ7PCBs and the meteorological conditions were analyzed, aiming to quantify the pollution level of PCBs in urban air. All the samplers were extracted by accelerated solvent extraction (ASE) and analyzed by gas chromatography (GC). The monthly concentrations of Σ7PCBs were 81.4-2335.2 fg/m³. A distinct seasonal variation of PM₁₀-associated PCBs exhibited. Higher concentrations of PCBs in cold weather than warm weather was found. PCB28 and PCB52 were the major components of PM₁₀-associated PCBs in cold weather, while PCB 118 and PCB 180 dominated in warm weather. The fresh emission sources in cold weather, such as the burning of coal for domestic heating, were suggested to be a major influence factor. A significant correlation (p<0.05) was found between the total PCB congeners and atmospheric pressure. Heavy rainfall can also impact PM₁₀-PCBs significantly. The weak correlation coefficient between atmospheric PCBs and wind speed suggested that the inefficient dispersion and no significant pollution sources around.

Abstract: The monitor terminal (Single Chip Microcomputer 89c51) can be used as the portable device, also can be fixed at the farm to form the monitor terminal internet. It can be connected with the control center (the upper computer) by wired and wireless transmission. It can be functioned as the monitor by PCB design, the perceptual layer module design and the electric equipment controller design.