访问控制加密(access control encryption,ACE)是一种新颖的公钥加密概念,不仅可以保护数据的机密性,还实现了信息流向的控制.早期基于DDH(decisional Diffie-Hellman)假设的方案(DDH方案)存在密文泄露攻击且仅满足选择明文攻击(chosenp...访问控制加密(access control encryption,ACE)是一种新颖的公钥加密概念,不仅可以保护数据的机密性,还实现了信息流向的控制.早期基于DDH(decisional Diffie-Hellman)假设的方案(DDH方案)存在密文泄露攻击且仅满足选择明文攻击(chosenplaintextattack,CPA)安全,针对此类问题,密码学家提出了访问控制加密选择密文攻击(chosenciphertextattack,CCA)安全性定义,并基于Naor-Yung的构造策略构造了CCA安全的方案.但密码学家未修补DDH方案的安全瑕疵,且其CCA方案存在效率较低、构造复杂、通信策略受限等不足.将DDH方案进行了通用化设计,并以高效的方式修补了DDH方案遭受密文攻击的瑕疵,进一步,构造了CCA安全的访问控制加密方案,具有高效、设计简单、基于标准困难性假设的特点.最后,分别基于格上困难性假设和判定性双线性Diffie-Hellman(decisional binlinear Diffie-Hellman,DBDH)假设,给出了2种CCA安全方案的实例化设计。展开更多
Totally implantable access ports(TIAPs)are used for patients with poor peripheral vascular support requiring central venous access.In recent years,TIAPs have been gradually accepted and promoted by patients,doctors,an...Totally implantable access ports(TIAPs)are used for patients with poor peripheral vascular support requiring central venous access.In recent years,TIAPs have been gradually accepted and promoted by patients,doctors,and nurses owing to their advantages of convenient carrying,a long maintenance period,low complications,and a high quality of life for patients.Currently,medical personnel that handle TIAP implantation and management in China are from different areas of healthcare,including surgery,internal medicine,radiology,nurse anesthesia,vascular access,etc.,and many only handle TIAP as a part of their duties.Therefore,the operating procedures and steps for the diagnosis and treatment of complications of TIAP vary from person to person,resulting in different incidence and treatment methods for complications in the implantation and use of TIAP in different medical units.Based on this,we have updated the Shanghai expert consensus on TIAPs from 2015 and explored the diagnosis and treatment procedures of related complications while continuing to emphasize standardized implantation and maintenance.展开更多
Due to the gathering of sickrooms and consultation rooms in almost all hospitals, the performance of wireless devices system is deteriorated by the increase of collision probability and waiting time. In order to impro...Due to the gathering of sickrooms and consultation rooms in almost all hospitals, the performance of wireless devices system is deteriorated by the increase of collision probability and waiting time. In order to improve the performance of wireless devices system, relay is added to control the access point and then the access of devices is distributed. The concentration of access point is avoided and then the performance of system is expected to be improved. The discrete time Markov chain (DTMC) is proposed to calculate the access probability of devices in a duration time slot. The collision probability, throughput, delay, bandwidth and so on are theoretically calculated based on the standard IEEE802.15.6 and the performance of the system with and without relay is compared. The numerical result indicates that the performance of the system with control access point is higher than that of the system without control access point when the number of devices and/or packet arrive rate are high. However, the system with control access point is more complicated. It is the trade-off between the performance and the complication.展开更多
文摘Totally implantable access ports(TIAPs)are used for patients with poor peripheral vascular support requiring central venous access.In recent years,TIAPs have been gradually accepted and promoted by patients,doctors,and nurses owing to their advantages of convenient carrying,a long maintenance period,low complications,and a high quality of life for patients.Currently,medical personnel that handle TIAP implantation and management in China are from different areas of healthcare,including surgery,internal medicine,radiology,nurse anesthesia,vascular access,etc.,and many only handle TIAP as a part of their duties.Therefore,the operating procedures and steps for the diagnosis and treatment of complications of TIAP vary from person to person,resulting in different incidence and treatment methods for complications in the implantation and use of TIAP in different medical units.Based on this,we have updated the Shanghai expert consensus on TIAPs from 2015 and explored the diagnosis and treatment procedures of related complications while continuing to emphasize standardized implantation and maintenance.
文摘Due to the gathering of sickrooms and consultation rooms in almost all hospitals, the performance of wireless devices system is deteriorated by the increase of collision probability and waiting time. In order to improve the performance of wireless devices system, relay is added to control the access point and then the access of devices is distributed. The concentration of access point is avoided and then the performance of system is expected to be improved. The discrete time Markov chain (DTMC) is proposed to calculate the access probability of devices in a duration time slot. The collision probability, throughput, delay, bandwidth and so on are theoretically calculated based on the standard IEEE802.15.6 and the performance of the system with and without relay is compared. The numerical result indicates that the performance of the system with control access point is higher than that of the system without control access point when the number of devices and/or packet arrive rate are high. However, the system with control access point is more complicated. It is the trade-off between the performance and the complication.
