Amicable Orthogonal Designs of Order 8 for Complex Space-Time Block Codes

New amicable orthogonal designs AODs(8; 1; 1; 1; 2; 2; 2), AODs(8; 1; 1; 4; 1; 2; 2), AODs(8; 1; 2;2; 2; 2; 4), AODs(8; 1; 2; 2; 1; 2; 4), AODs(8; 1; 1; 2; 1; 2; 4), AODs(8; 1; 2; 4; 2; 2; 2), AODs(8; 1; 1; 4; 1; 1; 2; 2), AODs(8; 2; 2; 2; 2; 2; 2; 2; 2) and AODs(8; 1; 1; 1; 2; 1; 2; 2; 2) are found by applying a new theorem or by an exhaustive search. Also some previously undecided cases of amicable pairs are demonstrated to be non-existent after a complete search of the equivalence classes for orthogonal designs

Two complex orthogonal space-time codes for eight transmit antennas

Two new constructions of complex orthogonal space-time block codes of order 8 based on the theory of amicable orthogonal designs are presented and their performance compared with that of the standard code of order 8. These new codes are suitable for multi-modulation schemes where the performance can be sacrificed for a higher throughput

Inter-domain routing validator based spoofing defence system

IP spoofing remains a problem today in the Internet. In this paper, a new system called Inter-Domain Routing Validator Based Spoofing Defence System (SDS) for filtering spoofed IP packets is proposed . SDS uses efficient symmetric key message authentication code (UMAC) as its tag to verify that a source IP address is valid. Different ASes border routers obtain a shared key via the Inter-Domain Routing Validator (IRV) servers which will manage the secret keys and exchange keys among different ASes via security communication channel. SDS is efficient, secure and easy to cooperate with other defence mechanisms

Perceived occupational stressors among nurses in a level-1 trauma center under normalized COVID-19 epidemic prevention and control in China: A qualitative study

Background: Nurses in trauma centers encounter emergency patients and are exposed to occupational stressors under normalized pandemic control and prevention. Objective: The objective of this study was to examine the occupational stressors that nurses perceived during the COVID-19 pandemic in a level-1 trauma center in China. Methods: From December 2020 to May 2021, a qualitative study was conducted, employing conventional content analysis as the research methodology. A total of twelve nurses were purposefully selected from a trauma center at a major hospital in Beijing to participate in semi-structured interviews (40–50 min’ duration). The data collected in this study were analyzed using the conventional content analysis approach proposed by Graneheim and Lundman. Results: After analyzing the data, two themes emerged: 1) Critical conditions under normalized pandemic prevention and control; 2) Concerns about loved ones and colleagues, along with financial problems. Both these themes further revealed four categories: the complexity and uncertainty of epidemic prevention and health hazards in the former, and concerns for and from families and colleagues, and financial stress in the latter. Conclusions: The results of this study provide valuable insights into the practical implementation of epidemic prevention and control measures in Chinese trauma centers and shed light on the psychological stress faced by nurses. Improving the tripartite support system of hospital, family, and society, and providing emotional support may help reduce stress among nurses, thereby improving their health and care quality

Fault diagnosis of rigid cage guide based on wavelet packet and BP neural network

In view of problems that existing fault diagnosis methods of rigid cage guide could not eliminate influences of environmental factors and low recognition rate of joint faults, a method of fault diagnosis of rigid cage guide based on wavelet packet and BP neural network was proposed in order to improve accuracy of identification of fault types of rigid cage guide. Experimental platform of lifting system of vertical shaft was set up to simulate two typical fault types of rigid cage guide including step protrusion and joint failure, and vibration acceleration signal of lifting vessel was collected. Wavelet packet decomposition was applied to carry out energy analysis and extract fault characteristic parameters. The fault characteristic parameters were taken as input of BP neural network, and a new test sample was selected to detect diagnostic effect of the neural network. The experimental results show that the method has high accuracy of fault identification, and the confidence level reaches to 0.91

Culture Clash in the Boardroom (HBR CASE STUDY)

The article presents a case study about a fictional chemical-manufacturing joint venture in China that involves a German parent firm and its Chinese partner. The German firm has insisted upon scrupulous compliance with Western standards regarding industrial safety, business ethics, and the environment. However, its Chinese partners are annoyed that they cannot use gifts, commissions, and other favors said to be frequently used in China in order to secure business. Disagreement has arisen over whether the joint venture should pay a commission to a potential customer's purchasing agent in order to clinch a very large sale

An exposure property of block designs

An exposure property of block designs is defined and investigated in this paper. The families of c-exposed designs are shown for c = 2 and c = 3. A sufficient condition for a c-exposed design is derived