摘要：The hypercompressor is one of the core facilities in low density polyethylene production,with a discharge pressure of approximately 300 MPa.A packing cup is the basic unit of cylinder packing,assembled by the interference fit between an inner cup and an outer *** the shrink-fitting prestresses the packing cup,serious design is needed to gain a favorable stress state,for example,a tri-axial compressive stress *** traditional method of designing the interference fit value for packing cups depends on the shrink-fit theory for thickwalled cylinder subject to internal and external *** to the traditional method,critical points are at the inner radii of the inner and external *** this study,the finite element method(FEM)has been implementcd to determine a more accurate stress level of packing *** critical points have been found at the edge of lapped sealing surfaces between two adjacent packing *** maximum Von Mises equivalent stress in a packing cup increases after a decline with the rise of the interference fit *** maximum equivalent stress initially occurs at the bore of the inner cup,then at the edge of lapped mating surfaces,and finally at the bore of the outer cup,as the interference radius *** traditional method neglects the influence of axial preloading on the interference mating *** a result,it predicts a lower equivalent stress at the bore of the external cup.A higher interference fit value accepted by the traditional method may not be feasible as it might already make packing cups yield at the edge of mating surfaces or the bore of the external *** with fatigue analysis,the feasible range of interference fit value has been modified by utilizing *** modified range tends to be narrower and safer than the one derived from the traditional method,after getting rid of shrink-fit values that could result in yielding in a real packing cup.

摘要：Wireless relaying has been known to provide the improvements in link reliability, spectral efficiency, and coverage extension. In this paper, we use full duplex relays for interference Alignment (IA) in K-users interference Channel (IC) and show K Degrees of Freedom (DOF) is achievable. In first hop, relays receive signals from transmitters and forward them to receivers in second hop. Two iteratively algorithms are proposed for computing relays function, precoder, and decoder matrices. First algorithm minimizes leakage interference at receivers that has appropriate performance at high Signal to Noise Ratio (SNR) region. Furthermore, the second algorithm has better performance at low-mediate SNR. The performance of proposed algorithms are compared with other schemes and validated with simulation in terms of achieved sum rate.

摘要：Wise arrangement of antennas is critical in wireless cellular systems for both reductions of co-channel interference (CCI) and increase the quality of service (QoS). In this paper, a novel architecture for antenna arrangement in CDMA wireless cellular systems is presented. In this architecture that we called Microzone, every cell is divided into three (or more) zones and information transmission in downlink channel is done by an antenna which is placed at the outer region of the related zone. Also, the transmitting signal by the mobile station (MS) in uplink channel is received by all the antennas of the related cell. Analytical calculations of the received signal to noise ratio (SIR) and outage probability for both microzone and used architectures show that proposed architecture has better performance in compared with the used architecture. Also, simulation results confirm lower outage probability in uplink channel for microzone architecture.

摘要：目的 构建靶向性血小板衍生生长因子(PDGF)B链的小分子干扰RNA(siRNA)表达质粒,为进一步研究PDGF基因功能奠定基础.方法 根据PDGF-B链序列设计合成含靶向PDGF基因siRNA转录模板的茎环结构,与两端分别有Bam HI、HindIII酶切位点的pSilencer3.1-Hlhygro质粒连接,转化大肠杆菌,扩增、纯化得到所需质粒,通过琼脂糖凝胶电泳及基因测序鉴定其分子量及插入片段的序列.结果 PCR扩增片段与预期结果相符,双酶切证实PDGF siRNA表达载体克隆构建成功,插入片段测序结果与合成的siRNA结果一致.结论 成功构建了靶向性PDGF基因的siRNAs表达质粒.

摘要：目的 构建pGPU6/GFP/Neo-shRNA-CTGF重组质粒（简称shRNA-CTGF）,通过RNA干扰（RNAi）技术对结缔组织生长因子（connective tissue growth factor,CTGF）进行体内、体外干预,分析其对瘢痕疙瘩Ⅰ型胶原蛋白（collagen-Ⅰ,COL-Ⅰ）表达的影响.方法 设计并构建特异性shRNA-CTGF重组质粒,RNAi转染体外培养瘢痕疙瘩成纤维细胞（keloid fibroblast,KFB）,检测CTGF基因沉默情况及KFB分泌的COL Ⅰ量;将shRNA-CTGF重组质粒对构建的裸鼠瘢痕疙瘩动物模型进行体内转染,检测CTGF基因沉默情况及COL-Ⅰ基因、蛋白表达水平.结果 成功构建了CTGF重组质粒,其在体内、体外环境下均可成功沉默CTGF表达,其抑制率为86.8％和54.1％;RNA体外干扰KFB定向沉默CTGF的同时可显著抑制COL-Ⅰ表达,其mRNA、蛋白水平抑制率分别为76.8％和65.6％;RNA体内干预实验也可显著降低COL-Ⅰ表达,其mRNA、蛋白水抑制率分别为52.7％和48.0％.结论 shRNA-CTGF重组质粒在体外及体内环境下均可成功沉默CTGF基因表达,沉默CTGF能显著降低瘢痕疙瘩中COL-Ⅰ蛋白含量,提示CTGF基因是病理性瘢痕治疗的潜在靶点.