Effective quality factors for neutrons based on the revised ICRP/ICRU recommendations

The quality factor (Q) is intended to relate the biological effectiveness of a radiation to the absorbed dose delivered in tissue. Quality factors are defined as a function of the unrestricted linear energy transfer (L) relationship in water and are used with operational quantities. Radiation weighting factors (wR) are used in protection quantities to take into account total radiation detriment. While the International Commission on Radiological Protection (ICRP) defines the Q(L) relationship, the International Commission on Radiation Units and Measurements (ICRU) recommends the charged particle stopping power and range data. If either of these data recommendations change, the quality factors must be recomputed. The latest guidance from both organisations applicable to neutron quality factors are the ICRP Publication 60 (Q(L) relationship) and the ICRU Report 49 (stopping power and range data). In the present study, absorbed dose conversion coefficients (pGy cm2) were calculated for two operational quantities defined by the ICRU--the ambient absorbed dose and the personal absorbed dose. Dose-equivalent (pSv cm2) conversion coefficients were also computed using mean quality factors based on ICRP 60 and ICRU 49 recommendations. Effective quality factors were then calculated from the ratio of the dose-equivalent to the absorbed dose conversion coefficients for both the personal dose-equivalent and ambient dose-equivalent and compared to values reported in the literature.     

热舒适空调的能量设计因子研究

为确定热舒适需求与空调节能设计过程中的关键能量设计要素之间的关联性,提出了一种基于热舒适的空调能量设计因子提取及其重要度计算方法。在热舒适空调节能设计过程框架的基础上,建立了基于热舒适需求的功能质量屋,并将热舒适性转化为空调功能及权重等设计信息;分析功能的能量特性,针对与能耗相关的功能,给出了能量设计因子提取策略,以及能量设计因子对热舒适及能耗综合影响程度量化方法。以家用空调为例,提取了基于热舒适的能量设计因子,对容积效率和传热系数两项耦合因子进行了分解,并对整体层能量设计因子的热舒适性及能耗的影响系数进行计算,按综合影响系数由大到小排序,结果为压缩机功率、系统控制方式、通风量和换热量。     

Image Quality in Photographic Microreproduction

The importance of the different parameters determining image quality in photographic microreproduction is discussed. In a first section it is shown that the slope of the H. & D.-curve is limited, among other factors, by the modulation transfer function of the complete system. In a second section the relation between information capacity. resolving power and practical image quality is considered. It is shown that a linear combination of image spread and granularity provides a good criterion for image quality.     

R404A在小管径管内流动沸腾换热特性研究

R404A在小管径管内的流动沸腾换热过程是一个极其复杂的物理现象。目前对R404A换热特性的研究大多集中在大管径上,对小管径换热特性的研究较少,且对不同实验现象的机理分析也不尽相同。因此R404A在小管径管内换热特性的理论研究仍需要大量具体的实验数据来支撑。本文通过搭建小管径内螺纹铜管蒸发实验台,研究R404A在小管径管内流动沸腾换热过程中不同热流密度、不同蒸发干度、不同质流密度、不同饱和温度对表面传热系数的影响,研究表明:热流密度、干度、质流密度、饱和温度均对R404A在小管径管内换热特性的影响较大,干涸现象发生前后这些因素产生的影响也不同。此外,这些因素对管内干涸现象发生的起始干度、沸腾主要换热形式以及干涸现象是否发生具有直接影响。     

Inductor Modeling in Wireless Links for Implantable Electronics

This paper describes the ac power dissipation of coils as well as their self-capacitance, self-resonant frequency, and quality factor Q. In the past, self-resonant frequency was rarely calculated during design because of the lack of suitable closed-form design equations. However, coils are widely used in biomedical applications as inductive links for both power and data, and the power transfer capacity and the data rate of inductive links are determined by the operating frequency of the coils. The maximum operating frequency is limited by the self-resonant frequency of the coil. We present here an analytical express for the optimal frequency of a coil in terms of the design parameters. By varying the design parameters, we can move the optimal frequency close to the operating frequency, thereby boosting the efficiency of the inductive link. We have verified the derivation experimentally and shown it to be useful in optimizing coil Index performance.     

热转移印刷中承印物热力学性能的研究

热转移印刷中温度及压力是影响印刷质量的关键因素,通过对热转移印刷中承印物的热力学性能研究,分析了承印物在高温条件下的蠕变曲线,以及热转移印刷中转印温度、转印时间及印刷压力对热转移印刷质量的影响,为实际印刷操作中转印温度的控制,转印时间及印刷压力的确定提供理论依据。     

Efficiency of excitation of piezoceramic transducers at antiresonance frequency

The efficiency of piezoceramic transducers excited at both the resonance and antiresonance frequency was investigated. Losses in piezoceramics are phenomenologically considered to have three coupled mechanisms: dielectric, mechanical, and piezoelectric losses. Expressions for the resonance and antiresonance quality factors, which ultimately determine transducer efficiency, have been received on the basis of complex material constants for both stiffened and unstiffened vibration modes. Comparison of electric and mechanical fields, thermal and electrical losses of power supply, and their distribution in the transducer volume have been made. For a given constant mechanical displacement of the transducer top, the required electric voltage applied to the transducer at the antiresonance frequency is proportional to the resonance quality factor, but the changes in the intrinsic electric and mechanical field characteristics in the common case are not too essential. The requirements on the piezoceramic parameters, types of transducer vibration, and especially on the factor of piezoelectric losses in a range of physically valid values were established to provide maximal quality factors at the antiresonance frequency.     

循环液物性对地源热泵性能影响因素分析

讨论了在不同换热器类型、防冻液种类、浓度和温度条件下循环液物性参数对换热的影响.通过引入传热衰减系数,讨论了添加防冻剂对热泵机组换热器换热效果的影响,并分别在制冷工况和制热工况下给出了不同种类和浓度的防冻液所对应的换热面积修正系数和循环水泵功率的变化.     

Effect of process parameters and optimization of CO2 laser cutting of ultra high-performance polyethylene

The aim of this work is to relate the cutting edge quality parameters (responses) namely: upper kerf, lower kerf, ratio of the upper kerf to lower kerf and cut edge roughness to the process parameters considered in this research and to find out the optimal cutting conditions. The process factors implemented in this research are: laser power, cutting speed and focal point position. Design of experiment (DoE) was used by implementing Box-Behnken design to achieve better cut qualities within existing resources. Mathematical models were developed to establish the relationship between the process parameters and the edge quality parameters. Also, the effects of process parameters on each response were determine. Then, a numerical optimization was performed to find out the optimal process setting at which the quality features are at their desired values. The effect of each factor on the responses was established and the optimal cutting conditions were found.     

融合书画艺术元素的家居软装饰图案优化设计及应用

目的 利用中国书画元素对家居软装饰图案进行优化设计。方法 在分析中国书画艺术元素特点和内容的基础上,结合家居软装饰的构成因素及风格特征,将构图、线条、赋色和笔墨应用于软装饰的优化设计中。随后将基于卷积神经网络的超分辨率模型(Efficient Sub-Pixel Convolutional Neural Network,ESPCN)与Laplace算子相结合,形成Laplace-ESPCN模型,由此进行整体装饰图案的迁移,提出了基于泊松融合的局部迁移方法并加以完善。结果 所提出的整体装饰图案迁移模型在噪声密度超过50%时,品质因素仍然在0.5左右,并且峰值信噪比最低可达40 dB。将其与泊松融合的局部迁移结合后,目标区域分割下人数占比均在50%附近。结论 所提出的Laplace-ESPCN整体图案迁移模型得到的图像质量较高,具有更好的降噪效果。与泊松融合的局部迁移方法结合后,所得图像边缘更加平滑,可以在家居软装饰图案优化设计中有效应用,具有一定的推广价值。     

Design and implementation of a novel power factor monitoring unit using discrete wavelet transform

Design and implementation of a novel on-line single-phase power factor measurement technique under non-sinusoidal and time-varying environments are presented. The proposed method expresses true power factor in terms of displacement and distortion power factors under certain significant facts, as defined in IEEE Std. 1459- 2000. The displacement power factor is evaluated using a unique digital signal-processing algorithm, whereas discrete wavelet transform (DWT) based multi-resolution analysis has been proposed for an accurate estimation of distortion power factor. An efficient algorithm to perform DWT in real time, using Texas Instruments TMS320VC5416 digital signal processor, has also been discussed. Illustrative laboratory test results confirm the validity and accurate performance of the proposed method for tracking true power factor under both static and dynamic situations.     

Experimental Investigation of Thermal Performance in a Concentric-Tube Heat Exchanger with Wavy Inner Pipe

In this article, the heat transfer, friction factor, and thermal performance factor characteristics of a concentric-tube heat exchanger are examined experimentally. A wavy inner pipe is mounted in the tube with the purpose of generating swirl flow that would help to increase the heat transfer rate of the tube. The examination is performed for a Reynolds number ranging from 2700 to 8800. An empirical correlation is also formulated to match with experimental data of the Nusselt number using the Wilson plot method. In addition, to obtain the real benefits in using the swirl generator at a constant pumping power, the thermal enhancement factor is also determined. Over the range considered, the increases in the Nusselt number, friction factor, and thermal performance factor are found to be, respectively, about 113?%, 81?%, and 196?% higher than those obtained from a smooth-surface inner pipe.     

Quantities and units in radiation protection

In its Publication No. 60, the International Commission on Radiological Protection (ICRP) introduced a new quantity, the equivalent dose in tissue, HT = sigma R WR DT.R where DT.R is the absorbed dose averaged over the tissue or organ, T, and WR is the radiation weighting factor. The latter depends on the incident radiation, i.e., the type and energy, but is independent of the tissue. On the other hand, a customarily defined quantity, the 'dose equivalent' is maintained (in particular the operational dose-equivalent quantities introduced in ICRU Report 39), but the relationship between the quality factor Q(L) and the linear energy transfer, L, has been redefined. In the case of neutrons, this procedure gives rise to an increase of the corresponding fluence to dose-equivalent conversion factors. The reasons for introducing these and the new tissue-weighting factor changes are discussed.     

振动主动控制系统的统计能量分析

基于能量观点对振动主动控制系统进行了统计能量分析。首次推导出振动主动控制系统的统计能量关系式和耦合振子间耦合损耗因子的表达式,并通过实例研究了控制反馈系数对系统耦合损耗因子的影响,分析了阻尼对系统输入功率、子系统间传递功率流以及各子系统振动能量的影响。     

脉冲调宽乘法器在交流应用下的误差及标准功率、电压、电流测量仪的研制

本文讨论了脉冲调宽乘法器用于交流测量时交直流变换误差与时分割频率的关系，提出了一种新的准确计算方法，并对相移误差等因素作了分析，给出了减小误差的措施。最后介绍了基于上述分析而设计研制的标准功率、电压、电流测量仪，其测量功率、电压、电流的误差均小于００１％     

美术专用纸对数码输出影像质量及耐久性的影响

影响数码输出喷墨打印的影像质量及耐久性的因素很多。影响数码影像质量的因素有：输入原照片的质量，打印机的分辨率，数码相机的像素，CCD芯片的大小和分辨率等；影响数码影像耐久性的因素有温度、湿度、有害化学气体、灰尘、所用纸、墨等，其中主要影响输出数码影像质量和耐久性的直接因素是纸和墨。     

Modelling distributed generations in three-phase distribution load flow

The mathematical models of distributed generations (DGs) are integrated into three-phase distribution load flow program to analyse and simulate the penetrations of DGs for distribution systems. DGs can utilise the traditional energy sources such as oil and coal or renewable energy sources such as wind, solar and fuel cell and use rotating generators or converters to transfer energy to power grids. According to the characteristics of output power, DGs can be specified as constant power factor model, constant voltage model or variable reactive power model in the load flow analysis. These three models are all derived and integrated into the proposed load flow method. Test results demonstrate the validity and capability of the proposed method.     

R404A condensing under forced flow conditions inside smooth, microfin and cross-hatched horizontal tubes

Two-phase heat transfer coefficient characteristics of R404A condensing under forced flow conditions inside smooth, microfin and cross-hatched horizontal tubes are experimentally investigated. Experimental parameters include a lubricating polyol ester oil concentration varied from 0 to 4%. The test runs were done at average inlet saturated condensing temperatures of 40 °C. The inlet vapor was kept at saturation (quality=1.0). The mass fluxes were between 200 and 600 kg/m² s, and the heat fluxes were selected to obtain a quality of 0.0 at the outlet of the test section, varying from 5 to 45 kW/m². The heat transfer enhancement factor varied between 1.8 and 2.4 for both microfin and cross-hatched tubes. The larger values applied for larger mass fluxes for the cross-hatched tube and smaller mass fluxes for the microfin tube. Enhancement factors increased as oil concentration increased up to oil concentrations of 2%. For higher oil concentrations the enhancement decreased especially at high mass fluxes, the cross-hatched tube being less sensitive to oil contamination. Pressure drop in the test section increased by approximately 25% as the oil concentration increased from 0 to 4%. The results from the experiments are compared with those calculated from correlations reported in the literature. Moreover, modified correlations for the condensation heat transfer coefficient are proposed for practical applications.     

Single-stage unity power factor based electronic ballast

This paper deals with the design, modeling, analysis and implementation of unity power factor (UPF) based electronic ballast for a fluorescent lamp (FL). The proposed electronic ballast uses a boost AC–DC converter as a power factor corrector (PFC) to improve the power quality at the input ac mains. In this single-stage UPF based electronic ballast, boost PFC converter and a half bridge series resonant inverter (HBSRI) share a common power switch. Thus one power switch is reduced as compared to the conventional two-stage approach. The design, modeling, analysis and implementation of this topology were carried out in MATLAB-Simulink environment for a T8 36 W, 220 V, 50 Hz fluorescent lamp. The switching frequency was kept more than the resonant frequency of the inverter, to ensure the zero voltage switching (ZVS) operation of both power switches. This resulted in reduction of high frequency switching losses. The power quality parameters such as displacement power factor (DPF), distortion factor (DF), power factor (PF), crest factor (CF) and total harmonic distortion of ac mains current (THD_i) were evaluated to analyze the performance of proposed electronic ballast. Test results on a developed prototype of PFC electronic ballast were included to validate the design and simulated results.