A new node-pairs contact algorithm is proposed to deal with a composite material or bi-material interface crack face contact and friction problem （e.g., resistant coating and thermal barrier coatings） subjected to c...A new node-pairs contact algorithm is proposed to deal with a composite material or bi-material interface crack face contact and friction problem （e.g., resistant coating and thermal barrier coatings） subjected to complicated load conditions. To decrease the calculation scale and calculation errors, the local Lagrange multipliers are solved only on a pair of contact nodes using the Jacobi iteration method, and the constraint modification of the tangential multipliers are required. After the calculation of the present node-pairs Lagrange multiplier, it is turned to next contact node-pairs until all node-pairs have finished. Compared with an ordinary contact algorithm, the new local node-pairs contact algorithm is allowed a more precise element on the contact face without the stiffness matrix singularity. The stress intensity factors （SIFs） and the contact region of an infinite plate central crack are calculated and show good agreement with those in the literature. The contact zone near the crack tip as well as its influence on singularity of stress fields are studied. Furthermore, the frictional contacts are also considered and found to have a significant influence on the SIFs. The normalized mode-II stress intensity factors KII for the friction coefficient decrease by 16% when f changes from 1 to 0.展开更多
目的:评价腹腔镜辅助全胃切除术(laparoscopic-assisted total gastrectomy,LATG)及D2淋巴结清扫术的可行性、安全性、肿瘤根治性及术后早期疗效。方法:回顾分析为32例胃癌患者行腹腔镜辅助全胃根治术的临床资料,以性别、年龄、体重指数...目的:评价腹腔镜辅助全胃切除术(laparoscopic-assisted total gastrectomy,LATG)及D2淋巴结清扫术的可行性、安全性、肿瘤根治性及术后早期疗效。方法:回顾分析为32例胃癌患者行腹腔镜辅助全胃根治术的临床资料,以性别、年龄、体重指数、ASA评分、术前总蛋白、白蛋白、血红蛋白、术前是否接受新辅助化疗、UICC(1997)分期、肿瘤部位、病理组织学类型及Bormann分型为指标,用逐一配对法选择同期32例传统开腹手术作为对照,比较两组的手术安全性、术后恢复及肿瘤的根治性。结果:32例均成功完成腹腔镜手术,无中转开腹。27例施行LATG(D2),1例行腹腔镜辅助全胃联合胰体尾切除术(D2),5例行腹腔镜辅助姑息全胃切除术。腹腔镜组平均手术时间(220.78±44.34)min,开腹组(178.44±29.06)min(P<0.05)。腹腔镜组平均切口长度、术后肛门排气时间及进食时间分别为(5.50±0.57)cm,(3.63±1.04)d,(3.94±0.84)d,显著低于开腹组。腹腔镜组术后第1天白细胞及中性粒细胞计数分别增加(6.61±2.92)×109/L,(7.32±3.01)×109/L,第3天白细胞及中性粒细胞分别增加(3.99±3.83)×109/L,(4.48±3.94)×109/L,显著低于开腹组。腹腔镜组淋巴结清扫总数、第1及第2站淋巴结数分别为(26.41±13.71)、(17.13±9.13)及(9.22±8.16)枚,与开腹组差异无统计学意义。腹腔镜组切口感染率低于开腹组,肺部感染率高于开腹组,但差异无统计学意义;两组其他并发症及总的并发症发生率差异亦无统计学意义。术后近期随访效果良好。结论:LATG比传统开腹手术时间长,但能达到与开腹根治性全胃切除术(D2)相同的淋巴结清扫范围,且具有患者创伤小、术后急性期反应轻、术后康复快等优势,LATG安全、可行、微创。展开更多
In this paper,we investigate covert communications in data collected IoT with NOMA,where the paired sensor nodes S_(m) and S_(n) transmit covert messages to a legitimate receiver(Bob)in the presence of a Warden(Willie...In this paper,we investigate covert communications in data collected IoT with NOMA,where the paired sensor nodes S_(m) and S_(n) transmit covert messages to a legitimate receiver(Bob)in the presence of a Warden(Willie).To confuse the detection at Willie,an extra multi-antenna friendly jammer(Jammer)has been employed to transmit artificial noise(AN)with random power.Based on the CSI of Willie is available or not at Jammer,three AN transmission schemes,including null-space artificial noise(NAN),transmit antenna selection(TAS),and zeroforcing beamforming(ZFB),are proposed.Furthermore,the closed-form expressions of expected minimum detection error probability(EMDEP)and joint connection outage probability(JCOP)are derived to measure covertness and reliability,respectively.Finally,the maximum effective covert rate(ECR)is obtained with a given covertness constraint.The numerical results show that ZFB scheme has the best maximum ECR in the case of the number of antennas satisfies N>2,and the same maximum ECR can be achieved in ZFB and NAN schemes with N=2.Moreover,TAS scheme also can improve the maximum ECR compared with the benchmark scheme(i.e.,signal-antenna jammer).In addition,a proper NOMA node pairing can further improve the maximum ECR.展开更多
基金supported by the National Basic Research Program of China(Grant No.2012CB026200)the National Natural Science Foundation of China(Grant No.50878048)
文摘A new node-pairs contact algorithm is proposed to deal with a composite material or bi-material interface crack face contact and friction problem （e.g., resistant coating and thermal barrier coatings） subjected to complicated load conditions. To decrease the calculation scale and calculation errors, the local Lagrange multipliers are solved only on a pair of contact nodes using the Jacobi iteration method, and the constraint modification of the tangential multipliers are required. After the calculation of the present node-pairs Lagrange multiplier, it is turned to next contact node-pairs until all node-pairs have finished. Compared with an ordinary contact algorithm, the new local node-pairs contact algorithm is allowed a more precise element on the contact face without the stiffness matrix singularity. The stress intensity factors （SIFs） and the contact region of an infinite plate central crack are calculated and show good agreement with those in the literature. The contact zone near the crack tip as well as its influence on singularity of stress fields are studied. Furthermore, the frictional contacts are also considered and found to have a significant influence on the SIFs. The normalized mode-II stress intensity factors KII for the friction coefficient decrease by 16% when f changes from 1 to 0.
文摘目的:评价腹腔镜辅助全胃切除术(laparoscopic-assisted total gastrectomy,LATG)及D2淋巴结清扫术的可行性、安全性、肿瘤根治性及术后早期疗效。方法:回顾分析为32例胃癌患者行腹腔镜辅助全胃根治术的临床资料,以性别、年龄、体重指数、ASA评分、术前总蛋白、白蛋白、血红蛋白、术前是否接受新辅助化疗、UICC(1997)分期、肿瘤部位、病理组织学类型及Bormann分型为指标,用逐一配对法选择同期32例传统开腹手术作为对照,比较两组的手术安全性、术后恢复及肿瘤的根治性。结果:32例均成功完成腹腔镜手术,无中转开腹。27例施行LATG(D2),1例行腹腔镜辅助全胃联合胰体尾切除术(D2),5例行腹腔镜辅助姑息全胃切除术。腹腔镜组平均手术时间(220.78±44.34)min,开腹组(178.44±29.06)min(P<0.05)。腹腔镜组平均切口长度、术后肛门排气时间及进食时间分别为(5.50±0.57)cm,(3.63±1.04)d,(3.94±0.84)d,显著低于开腹组。腹腔镜组术后第1天白细胞及中性粒细胞计数分别增加(6.61±2.92)×109/L,(7.32±3.01)×109/L,第3天白细胞及中性粒细胞分别增加(3.99±3.83)×109/L,(4.48±3.94)×109/L,显著低于开腹组。腹腔镜组淋巴结清扫总数、第1及第2站淋巴结数分别为(26.41±13.71)、(17.13±9.13)及(9.22±8.16)枚,与开腹组差异无统计学意义。腹腔镜组切口感染率低于开腹组,肺部感染率高于开腹组,但差异无统计学意义;两组其他并发症及总的并发症发生率差异亦无统计学意义。术后近期随访效果良好。结论:LATG比传统开腹手术时间长,但能达到与开腹根治性全胃切除术(D2)相同的淋巴结清扫范围,且具有患者创伤小、术后急性期反应轻、术后康复快等优势,LATG安全、可行、微创。
基金supported by the National Natural Science Foundation of China under Grant(no.62071486,no.61771487,no.62171464).
文摘In this paper,we investigate covert communications in data collected IoT with NOMA,where the paired sensor nodes S_(m) and S_(n) transmit covert messages to a legitimate receiver(Bob)in the presence of a Warden(Willie).To confuse the detection at Willie,an extra multi-antenna friendly jammer(Jammer)has been employed to transmit artificial noise(AN)with random power.Based on the CSI of Willie is available or not at Jammer,three AN transmission schemes,including null-space artificial noise(NAN),transmit antenna selection(TAS),and zeroforcing beamforming(ZFB),are proposed.Furthermore,the closed-form expressions of expected minimum detection error probability(EMDEP)and joint connection outage probability(JCOP)are derived to measure covertness and reliability,respectively.Finally,the maximum effective covert rate(ECR)is obtained with a given covertness constraint.The numerical results show that ZFB scheme has the best maximum ECR in the case of the number of antennas satisfies N>2,and the same maximum ECR can be achieved in ZFB and NAN schemes with N=2.Moreover,TAS scheme also can improve the maximum ECR compared with the benchmark scheme(i.e.,signal-antenna jammer).In addition,a proper NOMA node pairing can further improve the maximum ECR.
