Cascade index modulation(CIM) is a recently proposed improvement of orthogonal frequency division multiplexing with index modulation(OFDM-IM) and achieves better error performance.In CIM, at least two different IM ope...Cascade index modulation(CIM) is a recently proposed improvement of orthogonal frequency division multiplexing with index modulation(OFDM-IM) and achieves better error performance.In CIM, at least two different IM operations construct a super IM operation or achieve new functionality. First, we propose a OFDM with generalized CIM(OFDM-GCIM) scheme to achieve a joint IM of subcarrier selection and multiple-mode(MM)permutations by using a multilevel digital algorithm.Then, two schemes, called double CIM(D-CIM) and multiple-layer CIM(M-CIM), are proposed for secure communication, which combine new IM operation for disrupting the original order of bits and symbols with conventional OFDM-IM, to protect the legitimate users from eavesdropping in the wireless communications. A subcarrier-wise maximum likelihood(ML) detector and a low complexity log-likelihood ratio(LLR) detector are proposed for the legitimate users. A tight upper bound on the bit error rate(BER) of the proposed OFDM-GCIM, D-CIM and MCIM at the legitimate users are derived in closed form by employing the ML criteria detection. Computer simulations and numerical results show that the proposed OFDM-GCIM achieves superior error performance than OFDM-IM, and the error performance at the eavesdroppers demonstrates the security of D-CIM and M-CIM.展开更多
As a highly sensitive and stable detector,refractive index detector is usually used for quantitative detection of substances such as polymer,sugar and organic acid. The research reviewed the application of HPLC-RID in...As a highly sensitive and stable detector,refractive index detector is usually used for quantitative detection of substances such as polymer,sugar and organic acid. The research reviewed the application of HPLC-RID in the fields of quantitative determination of medicine and food,in order to lay a foundation for wider use of RID.展开更多
Purpose: This study provides a simple protocol for validation of the gamma passing rates and to identify the optimum values of % dose and mm criteria for dose distributions measured with a detector array. Methods: We ...Purpose: This study provides a simple protocol for validation of the gamma passing rates and to identify the optimum values of % dose and mm criteria for dose distributions measured with a detector array. Methods: We chose ArcCHECK detector array to illustrate the concepts. We used plans with uniform or quasi-uniform dose distributions along the detector array for testing in the presence of dose errors. For testing sensitivity to spatial shift we employed a plan with approximately constant dose gradient along the axis of the instrument. Results: We identified a representative set of parameters which describe performance of a detector array. We determined the minimum gamma-index acceptance criteria allowing the passing rates to reach 100% in the absence of errors, and identified the minimum fully detectable errors for such criteria. For our baseline plans delivered to ArcCHECK, 100% passing rates were obtained for 1.5% dose criterion together with ±3% minimum error detectable at 100% rate, and for 1.5 mm criterion together with the minimum fully detectable error of ±3 mm. We inspected the impact of selected program options on the passing rates. Conclusions: The protocol we developed provides a simple method of commissioning-style analysis of a detector array without a need for analysis of a large number of clinical plans.展开更多
[目的]优化陕西耕地细碎化治理,协调粮食需求增长与环境约束之间的矛盾,维护地区粮食安全和促进农业现代化发展。[方法]以关中地区为研究区,以土地利用数据和其他自然经济数据为基础,运用洛伦兹曲线、变异系数法、景观指数、空间自相关...[目的]优化陕西耕地细碎化治理,协调粮食需求增长与环境约束之间的矛盾,维护地区粮食安全和促进农业现代化发展。[方法]以关中地区为研究区,以土地利用数据和其他自然经济数据为基础,运用洛伦兹曲线、变异系数法、景观指数、空间自相关等方法构建耕地细碎化评价模型以探索关中地区耕地细碎化(Cultivated Land Fragmentation,简称CLF)的时空变迁,并利用地理探测器对区内CLF进行了驱动力分析。[结果](1)关中地区耕地资源空间分布相对均衡,耕地专业化程度保持较高水平。(2)关中地区的CLF程度变化时空差异显著,CLF程度整体呈现下降态势,但部分地区CLF程度呈增减并存趋势,整体呈现东低西高的态势。(3)关中地区CLF时空分化受多种因素影响,社会经济因素的综合影响明显强于自然因素,其中海拔高度、人口密度、人均耕地面积和地区总产值GDP为主要影响因素;因子间的交互作用效应强于单因子,以双因子增强和非线性增强为主。[结论]关中地区耕地细碎化问题在20年间得到了一定程度的改善,但呈现出较大的地区差异,应进一步在社会经济因素方面对耕地细碎化现象加强综合治理,以推动关中地区农业机械化、现代化发展。展开更多
基金supported by National Natural Science Foundation of China (No. 61971149, 62071504, 62271208)in part by the Special Projects in Key Fields for General Universities of Guangdong Province (No. 2020ZDZX3025, 2021ZDZX056)+1 种基金in part by the Guangdong Basic and Applied Basic Research Foundation (No. 2021A1515011657)in part by the Featured Innovation Projects of Guangdong Province of China (No. 2021KTSCX049)。
文摘Cascade index modulation(CIM) is a recently proposed improvement of orthogonal frequency division multiplexing with index modulation(OFDM-IM) and achieves better error performance.In CIM, at least two different IM operations construct a super IM operation or achieve new functionality. First, we propose a OFDM with generalized CIM(OFDM-GCIM) scheme to achieve a joint IM of subcarrier selection and multiple-mode(MM)permutations by using a multilevel digital algorithm.Then, two schemes, called double CIM(D-CIM) and multiple-layer CIM(M-CIM), are proposed for secure communication, which combine new IM operation for disrupting the original order of bits and symbols with conventional OFDM-IM, to protect the legitimate users from eavesdropping in the wireless communications. A subcarrier-wise maximum likelihood(ML) detector and a low complexity log-likelihood ratio(LLR) detector are proposed for the legitimate users. A tight upper bound on the bit error rate(BER) of the proposed OFDM-GCIM, D-CIM and MCIM at the legitimate users are derived in closed form by employing the ML criteria detection. Computer simulations and numerical results show that the proposed OFDM-GCIM achieves superior error performance than OFDM-IM, and the error performance at the eavesdroppers demonstrates the security of D-CIM and M-CIM.
文摘As a highly sensitive and stable detector,refractive index detector is usually used for quantitative detection of substances such as polymer,sugar and organic acid. The research reviewed the application of HPLC-RID in the fields of quantitative determination of medicine and food,in order to lay a foundation for wider use of RID.
文摘Purpose: This study provides a simple protocol for validation of the gamma passing rates and to identify the optimum values of % dose and mm criteria for dose distributions measured with a detector array. Methods: We chose ArcCHECK detector array to illustrate the concepts. We used plans with uniform or quasi-uniform dose distributions along the detector array for testing in the presence of dose errors. For testing sensitivity to spatial shift we employed a plan with approximately constant dose gradient along the axis of the instrument. Results: We identified a representative set of parameters which describe performance of a detector array. We determined the minimum gamma-index acceptance criteria allowing the passing rates to reach 100% in the absence of errors, and identified the minimum fully detectable errors for such criteria. For our baseline plans delivered to ArcCHECK, 100% passing rates were obtained for 1.5% dose criterion together with ±3% minimum error detectable at 100% rate, and for 1.5 mm criterion together with the minimum fully detectable error of ±3 mm. We inspected the impact of selected program options on the passing rates. Conclusions: The protocol we developed provides a simple method of commissioning-style analysis of a detector array without a need for analysis of a large number of clinical plans.
文摘[目的]优化陕西耕地细碎化治理,协调粮食需求增长与环境约束之间的矛盾,维护地区粮食安全和促进农业现代化发展。[方法]以关中地区为研究区,以土地利用数据和其他自然经济数据为基础,运用洛伦兹曲线、变异系数法、景观指数、空间自相关等方法构建耕地细碎化评价模型以探索关中地区耕地细碎化(Cultivated Land Fragmentation,简称CLF)的时空变迁,并利用地理探测器对区内CLF进行了驱动力分析。[结果](1)关中地区耕地资源空间分布相对均衡,耕地专业化程度保持较高水平。(2)关中地区的CLF程度变化时空差异显著,CLF程度整体呈现下降态势,但部分地区CLF程度呈增减并存趋势,整体呈现东低西高的态势。(3)关中地区CLF时空分化受多种因素影响,社会经济因素的综合影响明显强于自然因素,其中海拔高度、人口密度、人均耕地面积和地区总产值GDP为主要影响因素;因子间的交互作用效应强于单因子,以双因子增强和非线性增强为主。[结论]关中地区耕地细碎化问题在20年间得到了一定程度的改善,但呈现出较大的地区差异,应进一步在社会经济因素方面对耕地细碎化现象加强综合治理,以推动关中地区农业机械化、现代化发展。
