目的探讨共刺激分子在慢性乙型肝炎病毒(hepatitis B virus,HBV)感染患者中的表达及对低复制与再活动阶段的表达意义。方法选取2016年2月至2017年2月保定市传染病医院收治的慢性HBV感染患者60例为研究组,选取同期健康体检人员60名为对照...目的探讨共刺激分子在慢性乙型肝炎病毒(hepatitis B virus,HBV)感染患者中的表达及对低复制与再活动阶段的表达意义。方法选取2016年2月至2017年2月保定市传染病医院收治的慢性HBV感染患者60例为研究组,选取同期健康体检人员60名为对照组,对比共刺激分子在研究对象中的水平及对低复制与再活动阶段的表达意义。结果研究组患者外周血当中CD_3^+、CD_4^+T及CD_4^+/CD_8^+的比值明显低于对照组,同时CD_8^+明显高于对照组(P<0.05);研究组患者的共刺激分子CD_(28)^+及细胞毒性T淋巴细胞抗原-4(CTLA-4)表达量均明显低于对照组(P<0.05),同时程序性死亡因子-1(PD-1)及T细胞球蛋白粘蛋白分子-3(Tim-3)表达明显高于对照组(P<0.05);HBV感染患者中的表达及对低复制与再活动阶段的表达意义方面,三组研究对象共刺激分子CTLA-4、CD_(28)^+、PD-1及Tim-3表达均存在明显区别(P均<0.05),高拷贝组患者的共刺激分子CTLA-4及CD_(28)^+表达均明显低于低拷贝组(P<0.05),同时PD-1及Tim-3表达量均明显高于低拷贝组(P<0.05)。结论借助于检测共刺激分子在慢性HBV感染患者当中的表达,可以准确体现患者免疫功能,对判断患者预后有一定指导价值。展开更多
A low-voltage, low-power, and high-gain rail-to-rail operational amplifier （OpAmp） is presented. The replica-amplifier gain enhancement technique is applied to improve the DC gain of the amplifier, which does not de...A low-voltage, low-power, and high-gain rail-to-rail operational amplifier （OpAmp） is presented. The replica-amplifier gain enhancement technique is applied to improve the DC gain of the amplifier, which does not degrade the output swing and is very suitable for low-voltage applications. In a 0. 18/μm standard CMOS process,a 1V OpAmp with rail-to-rail output is designed. For a load capacitance of 5 pF,simulation by HSPICE shows that this OpAmp achieves an effective open-loop DC gain of 65. 9dB,gain bandwidth of 70.28 MHz,and phase margin of 50 with a quiescent power dissipation of 156.7μW.展开更多
Ultra-high strength Al alloy system was developed by cryorolling and the contribution of various strengthening mechanisms to the overall yield strength of the system was evaluated. Cryorolling of Al-4%Cu-3%TiB2 in sit...Ultra-high strength Al alloy system was developed by cryorolling and the contribution of various strengthening mechanisms to the overall yield strength of the system was evaluated. Cryorolling of Al-4%Cu-3%TiB2 in situ composite followed by short annealing at 175 ℃ and ageing at 125℃ resulted in an ultra-high yield strength of about 800 MPa with 9%total elongation. The strengthening contributions form solid solution strengthening, grain refinement, dislocation strengthening, precipitation hardening and dispersion strengthening were evaluated using standard equations. It was estimated that the maximum contribution was from grain refinement due to cryorolling followed by precipitation and dispersion strengthening.展开更多
Performance of the Adaptive Coding and Modulation(ACM) strongly depends on the retrieved Channel State Information(CSI),which can be obtained using the channel estimation techniques relying on pilot symbol transmissio...Performance of the Adaptive Coding and Modulation(ACM) strongly depends on the retrieved Channel State Information(CSI),which can be obtained using the channel estimation techniques relying on pilot symbol transmission.Earlier analysis of methods of pilot-aided channel estimation for ACM systems were relatively little.In this paper,we investigate the performance of CSI prediction using the Minimum Mean Square Error(MMSE)channel estimator for an ACM system.To solve the two problems of MMSE:high computational operations and oversimplified assumption,we then propose the Low-Complexity schemes(LC-MMSE and Recursion LC-MMSE(R-LC-MMSE)).Computational complexity and Mean Square Error(MSE) are presented to evaluate the efficiency of the proposed algorithm.Both analysis and numerical results show that LC-MMSE performs close to the wellknown MMSE estimator with much lower complexity and R-LC-MMSE improves the application of MMSE estimation to specific circumstances.展开更多
In this study, an improved random access(RA) scheme for Machine-to-Machine(M2M) communications is proposed. The improved RA scheme is realized by two steps. First, the improved RA scheme achieves a reasonable resource...In this study, an improved random access(RA) scheme for Machine-to-Machine(M2M) communications is proposed. The improved RA scheme is realized by two steps. First, the improved RA scheme achieves a reasonable resource tradeoff between physical random access channel(PRACH) and physical uplink shared channel(PUSCH). To realize a low-complexity resource allocation between PRACH and PUSCH, a boundary of traffic load is derived to divide the number of active M2 M users(UEs) into multiple intervals. The corresponding resource allocation for these intervals is determined by e NB. Then the resource allocation for other number of UEs can be obtained from the allocation of these intervals with less computation. Second, the access barring on arrival rate of new UEs is introduced in the improved RA scheme to reduce the expected delay. Numerical results show that the proposed improved RA scheme can realize a low-complexity resource allocation between PRACH and PUSCH. Meanwhile, the expected delay can be effectively reduced by access barring on arriving rate of new M2 M UEs.展开更多
The carbon steels dispersed with ultrafine TiC particles were fabricated by conventional casting method. The casting process is more economical than other available routes for metal matrix composite production, and th...The carbon steels dispersed with ultrafine TiC particles were fabricated by conventional casting method. The casting process is more economical than other available routes for metal matrix composite production, and the large sized components to be fabricated in short processing time. However, it is extremely difficult to obtain uniform dispersion of ultrafine ceramic particles in liquid metals due to the poor wettability and the specific gravity difference between the ceramic particle and metal matrix. In order to solve these problems, the mechanical milling (MM) and surface-active processes were introduced. As a result, Cu coated ultrafine TiC powders made by MM process using high energy ball milling machine were mixed with Sn powders as a surfactant to get better wettability by lowering the surface tension of carbon steel melt. The microstructural investigations by OM show that ultrafine TiC particles are distributed uniformly in carbon steel matrix. The grain sizes of the cast matrix with ultrafine TiC particles are much smaller than those without ultrafine TiC particles. This is probably due to the fact that TiC particles act as nucleation sites during solidification. The wear resistance of cast carbon steel composites added with MMed TiC/Cu-Sn powders is improved due to grain size refinement.展开更多
We propose a low complexity robust beamforming method for the general-rank signal model, to combat against mismatches of the desired signal array response and the received signal covariance matrix. The proposed beamfo...We propose a low complexity robust beamforming method for the general-rank signal model, to combat against mismatches of the desired signal array response and the received signal covariance matrix. The proposed beamformer not only considers the norm bounded uncertainties in the desired and received signal covariance matrices, but also includes an additional positive semidefinite constraint on the desired signal covariance matrix. Based on the worst-case performance optimization criterion, a computationally simple closed-form weight vector is obtained. Simulation results verify the validity and robustness of the proposed beamforming method.展开更多
文摘目的探讨共刺激分子在慢性乙型肝炎病毒(hepatitis B virus,HBV)感染患者中的表达及对低复制与再活动阶段的表达意义。方法选取2016年2月至2017年2月保定市传染病医院收治的慢性HBV感染患者60例为研究组,选取同期健康体检人员60名为对照组,对比共刺激分子在研究对象中的水平及对低复制与再活动阶段的表达意义。结果研究组患者外周血当中CD_3^+、CD_4^+T及CD_4^+/CD_8^+的比值明显低于对照组,同时CD_8^+明显高于对照组(P<0.05);研究组患者的共刺激分子CD_(28)^+及细胞毒性T淋巴细胞抗原-4(CTLA-4)表达量均明显低于对照组(P<0.05),同时程序性死亡因子-1(PD-1)及T细胞球蛋白粘蛋白分子-3(Tim-3)表达明显高于对照组(P<0.05);HBV感染患者中的表达及对低复制与再活动阶段的表达意义方面,三组研究对象共刺激分子CTLA-4、CD_(28)^+、PD-1及Tim-3表达均存在明显区别(P均<0.05),高拷贝组患者的共刺激分子CTLA-4及CD_(28)^+表达均明显低于低拷贝组(P<0.05),同时PD-1及Tim-3表达量均明显高于低拷贝组(P<0.05)。结论借助于检测共刺激分子在慢性HBV感染患者当中的表达,可以准确体现患者免疫功能,对判断患者预后有一定指导价值。
文摘A low-voltage, low-power, and high-gain rail-to-rail operational amplifier （OpAmp） is presented. The replica-amplifier gain enhancement technique is applied to improve the DC gain of the amplifier, which does not degrade the output swing and is very suitable for low-voltage applications. In a 0. 18/μm standard CMOS process,a 1V OpAmp with rail-to-rail output is designed. For a load capacitance of 5 pF,simulation by HSPICE shows that this OpAmp achieves an effective open-loop DC gain of 65. 9dB,gain bandwidth of 70.28 MHz,and phase margin of 50 with a quiescent power dissipation of 156.7μW.
基金the Department of Science & Technology (DST) for their financial support for carrying out this research through Fast Track Scheme (DST Sanction No: SR/FT/ET-005/2008)Technical Education Quality Improvement Programme (TEQIP)
文摘Ultra-high strength Al alloy system was developed by cryorolling and the contribution of various strengthening mechanisms to the overall yield strength of the system was evaluated. Cryorolling of Al-4%Cu-3%TiB2 in situ composite followed by short annealing at 175 ℃ and ageing at 125℃ resulted in an ultra-high yield strength of about 800 MPa with 9%total elongation. The strengthening contributions form solid solution strengthening, grain refinement, dislocation strengthening, precipitation hardening and dispersion strengthening were evaluated using standard equations. It was estimated that the maximum contribution was from grain refinement due to cryorolling followed by precipitation and dispersion strengthening.
基金supported by the 2011 China Aerospace Science and Technology Foundationthe Certain Ministry Foundation under Grant No.20212HK03010
文摘Performance of the Adaptive Coding and Modulation(ACM) strongly depends on the retrieved Channel State Information(CSI),which can be obtained using the channel estimation techniques relying on pilot symbol transmission.Earlier analysis of methods of pilot-aided channel estimation for ACM systems were relatively little.In this paper,we investigate the performance of CSI prediction using the Minimum Mean Square Error(MMSE)channel estimator for an ACM system.To solve the two problems of MMSE:high computational operations and oversimplified assumption,we then propose the Low-Complexity schemes(LC-MMSE and Recursion LC-MMSE(R-LC-MMSE)).Computational complexity and Mean Square Error(MSE) are presented to evaluate the efficiency of the proposed algorithm.Both analysis and numerical results show that LC-MMSE performs close to the wellknown MMSE estimator with much lower complexity and R-LC-MMSE improves the application of MMSE estimation to specific circumstances.
基金supported by Key Laboratory of Universal Wireless Communications(Beijing University of Posts and Telecommunications),Ministry of Education,P.R.China,KFKT-2014103)National Science and Technology Major Project of China(No.2013ZX03006001)National Natural Science Foundation of China(61501056)
文摘In this study, an improved random access(RA) scheme for Machine-to-Machine(M2M) communications is proposed. The improved RA scheme is realized by two steps. First, the improved RA scheme achieves a reasonable resource tradeoff between physical random access channel(PRACH) and physical uplink shared channel(PUSCH). To realize a low-complexity resource allocation between PRACH and PUSCH, a boundary of traffic load is derived to divide the number of active M2 M users(UEs) into multiple intervals. The corresponding resource allocation for these intervals is determined by e NB. Then the resource allocation for other number of UEs can be obtained from the allocation of these intervals with less computation. Second, the access barring on arrival rate of new UEs is introduced in the improved RA scheme to reduce the expected delay. Numerical results show that the proposed improved RA scheme can realize a low-complexity resource allocation between PRACH and PUSCH. Meanwhile, the expected delay can be effectively reduced by access barring on arriving rate of new M2 M UEs.
基金supported by the Korea Atomic Energy Research Institute (KAERI) R&D Program
文摘The carbon steels dispersed with ultrafine TiC particles were fabricated by conventional casting method. The casting process is more economical than other available routes for metal matrix composite production, and the large sized components to be fabricated in short processing time. However, it is extremely difficult to obtain uniform dispersion of ultrafine ceramic particles in liquid metals due to the poor wettability and the specific gravity difference between the ceramic particle and metal matrix. In order to solve these problems, the mechanical milling (MM) and surface-active processes were introduced. As a result, Cu coated ultrafine TiC powders made by MM process using high energy ball milling machine were mixed with Sn powders as a surfactant to get better wettability by lowering the surface tension of carbon steel melt. The microstructural investigations by OM show that ultrafine TiC particles are distributed uniformly in carbon steel matrix. The grain sizes of the cast matrix with ultrafine TiC particles are much smaller than those without ultrafine TiC particles. This is probably due to the fact that TiC particles act as nucleation sites during solidification. The wear resistance of cast carbon steel composites added with MMed TiC/Cu-Sn powders is improved due to grain size refinement.
基金supported by the Fundamental Research Funds for the Central Universities,China(No.K5051202047)
文摘We propose a low complexity robust beamforming method for the general-rank signal model, to combat against mismatches of the desired signal array response and the received signal covariance matrix. The proposed beamformer not only considers the norm bounded uncertainties in the desired and received signal covariance matrices, but also includes an additional positive semidefinite constraint on the desired signal covariance matrix. Based on the worst-case performance optimization criterion, a computationally simple closed-form weight vector is obtained. Simulation results verify the validity and robustness of the proposed beamforming method.
