Search

The large-acceleration motion of HFV (hypersonic flight vehicle), the high-speed rolling of spinning missile, and the large-maneuver flight of fighter aircraft has put forward higher performance demand for SINS (strapdown inertial navigation system). The high-accuracy positing will be realized under the high-dynamic maneuver environment after decreasing measurement error of IMU (inertial measurement unit), meanwhile the algorithm of SINS must be improved. The conventional algorithm calculates the flight attitude with determining the compensation term of coning error, after ignoring the high-order term of the Bortz equation. To improve the algorithm accuracy of SINS under high-dynamic maneuver environment, a high-accuracy algorithm, which uses Legendre polynomial to complete angular velocity function approximation and takes the numerical method of quaternion differential equation as core, is proposed herein. The high-order coning error is compensated in the numerical solving period in the proposed novel algorithm, because no approximation exists in deducing process. The attitude calculating simulations are finished in coning motion condition and high-dynamic maneuver condition respectively. Compared with the quadruple-cross-product compensation algorithm which has the highest accuracy at present, the attitude error of proposed algorithm is less than its 1/3 in coning motion condition. And algorithm accuracy is raised an order of magnitude under the high-dynamic maneuver environment. The high-accuracy algorithm based on Legendre polynomial has reference significance for accurate positing of future HFV, atomic gyroscope INS research and high-accuracy algorithm design of SINS.

Wearing facial masks has been indicated as an effective way to reduce the risk of COVID-19 transmission among people. To get a deeper understanding of the habit of using face masks in normal life during COVID-19 outbreak and seek ways to solve the problems of mask using, we conducted a large-scale survey in China through online questionnaires. Totally 1004 respondents, including community outreach workers, non-healthcare professionals, retired people, and students participated in this study. Detailed information regarding the types of masks that people usually use, the habit of changing masks, the methods of mask cleaning, and the attitude toward reusing masks and their potential impact on the environment were collected and analyzed. Results show that more than 98% of people in China used masks during the pandemic, and the types of masks using and frequency of masks changing/reuse varied between different people. Moreover, most of the respondents had a healthy mask-changing habit for preventing the spread of COVID-19 and worried about the safety of mask reusing. The study would help enhance public awareness and develop policies for a better habit in face of the pandemic.

In this study, daily global solar radiation data at Urumuqi in 1995-2004 were investigated. Sunshine based models were used to estimate the global radiation. Estimated values were compared with measured values in terms of statistical error tests such as mean percentage error (MPE), mean bias error (MBE), root mean square error (RMSE). The model performing best was selected. The global solar radiation estimated from the best model was compared with measured values. It was determined that the predicted values have good agreement with the measured values at high daily global solar radiation.

In a university campus in Tianjin, four tents were set up to investigate the thermal environment and thermal comfort. Both the field investigation and questionnaires were adopted in this experiment. Two hundred people were investigated, and two hundred questionnaires were gotten. The results show that the thermal comfort zone of officers and soldiers is 24°C to 28°C in early fall, it is a wide range. There is a big error between the PMV index and the actual survey results, PMV calculation index is not accurate in tents environment. The results will have a significant effect on improving the thermal comfort of tents..

In order to improve knowledge on solar resources, this paper analyses the models correlating daily global solar radiation with sunshine duration for Wuhan, China. Estimated values were compared with measured values in terms of statistical error tests such as mean percentage error (MPE), mean bias error (MBE), root mean square error (RMSE). The model performing best was selected. The global solar radiation estimated from the best model was compared with measured values. It was determined that the predicted values have good agreement with the measured values at high daily global solar radiation.

Leptocybe invasa Fisher & La Salle (Hymenoptera, Eulophidae) is an invasive pest in Eucalyptus plantations throughout the world. Potential biological control agents for L. invasa were investigated in the Fujian, Guangdong, Hainan, Guangxi, Jiangxi, and Sichuan provinces of China, where Eucalyptus spp. have been severely damaged by the eucalyptus gall wasp. Three hymenopteran parasitoids of L. invasa were identified: Quadrastichus mendeli Kim & La Salle (Eulophidae), Aprostocetus causalis La Salle & Wu (Eulophidae), and Megastigmus viggianii Narendran & Sureshan (Torymidae); M. viggianii is newly recorded in China. The percentages of parasitization by Q. mendeli , A. causalis , and M. viggianii were 2.96%–19.53%, 2.30%–26.38%, and 24.93%, respectively. The longevity and body length of females were significantly greater than for males in A. causalis and M. viggianii . No males of Q. mendeli were found in China. These parasitoids could be used as biological agents for L. invasa in China.

Three models relating daily global solar radiation to sunshine duration has been investigated in order to estimate daily global radiation for Zhengzhou, China. The data from January 1995 to December 2004 have been used in the models. Comparison of the estimated and measured values showed that the cubic model was able to estimate global radiation at high daily global solar radiation.

Different black agricultural shading-nets were erected on two 93 type military cotton tents to improve the thermal environment of tents in this paper. Indoor temperature, RH (relative air humidity) and interior wall temperature were tested. The experimental results show that shading-nets a effect on the improvement of thermal environment and 6 needled filters shading-net is better than 3 needled filters shading-net. The conclusion of this paper provides a basis for the improvement of the thermal environment and energy saving design of the tent.