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[Objectives] The underwater landing of an Autonomous Underwater Vehicle(AUV)is a way to achieve underwater long-term latency and fixed-point observation which is conductive to the better control of changes in the marine environment.[Methods] This paper mainly introduces the fundamental structure and main functions of an AUV which is based on the oil sac type variable buoyancy system. Two kinds of underwater landing strategies are established:controlled buoyancy vertical dive landing and sailing dive and controlled buoyancy vertical landing. The target point deviation,energy consumption and AUV take-off from the bottom are analyzed,and the actual underwater landing experimental verification is carried out in a lake.[Results] The experimental results show that the AUV is able to steadily land underwater and take off from the bottom safely with this variable buoyancy system. The control strategy of sailing dive and controlled buoyancy vertical landing can save more energy,and the landing point is more accurate than with the strategy of controlled buoyancy vertical diving.[Conclusions] As such,the control strategy of sailing dive and controlled buoyancy vertical landing is more in line with the demands of future practical application.

The mean impact value (MIV) method which is an effective factor weight analysis method was used to quantitatively analyze the effect weight of 15 impact factors on the aging properties of polycarbonate (chromatic aberration, tensile strength, elongation at break, and bending strength) and the corresponding exposure time, climatic factors and environmental factors. The impact factors were exposure time, mean temperature, humidity, sunshine hours, precipitation, wind speed, sea salt ion, SO2, HCl, NO2, H2S, sulfation rate, NH3, water soluble dust fall, and non-water soluble dust fall. The results show that with the regulation rate increasing from 15% to 25% gradually, for the certain aging property, the effect weight of certain impact factor change little, while the sensitivities of aging properties to various impact factors are different; the climatic factors and exposure time are the greatest factors influencing the aging properties of polycarbonate, among environmental factors, the influence of dust fall quantity on the aging properties is the largest; exposure time is the main impact factor influencing chromatic aberration and elongation at break, mean relative humidity has the greatest impact on tensile strength and bending strength.

Traumatic blunt aortic injury especially on proximal ascending aorta is a rare injury with a few reports. Generally emergency surgical management was performed. In this case, however, in multiple trauma with brain injury, emergency surgical management of aortic injury might result in unexpected secondary injury of the brain. Herein, we report a case of a 33-year-old man who was driving a truck was injured in a head-on collision. Evaluation revealed a pseudoaneurysm on his ascending aorta concomitant with epidural hemorrhage. He was treated by surgical management of his ascending aorta after 3 days from accident. There were no postoperative and neurologic complications and the patient was discharged after 18 days.

Upper extremity deep vein thrombosis (DVT) is an unusual condition compared to lower extremity DVT, and it represents about 10% of all DVTs. We report a case of upper extremity DVT after clavicle fracture and immobilization.

We built a three-dimensional finite element (FE) model to investigate the impact response of fiber-metal laminates (FMLs). This FE model comprises two metal layers as facesheets and a carbon woven fabric-reinforced plastic laminate as inner core. Simulation was performed on ABAQUS/Explicit platform, and stiffness progressive degeneration criteria were implemented to evaluate damages in composites. The Johnson-Cook model was selected to calculate failures in metal, while surface-based cohesive behavior was adopted to simulate the delamination phenomenon. We studied the fiber stacking sequence, panel thickness, and incident angle effect on the impact behavior of FMLs. The critical penetration energy of the FMLs was determined, and the impact parameter history was discussed.

Optimization design and manufacturing play an important role in obtaining successful composite structures with high efficiency and safe use of materials. In this paper, we first present the optimization design procedure for a composite box girder by ANSYS parametric design language (APDL) in the ANSYS software. The input parameters used in the simulation work were determined via fundamental experimental tests of composite specimens. Then we manufactured the designed composite box girder by mold-pressing prepreg technology according to the optimization results. The finial composite girder structure composed of arch top, web and bottom composite plate was obtained. The optimization procedure indicated that the use of stiffening plates in a girder could decrease the weight and increase the failure load. The location and ply mode of the stiffening plates in girder were suggested. The three-point-bending test was performed on the girder, and the test indicated that load-carrying capacity in unit mass of the optimized girder was as high as 107.8 N/g. Simulation and experimental results match well, and the maximum and minimum stresses in each layer were within the strength limitation of carbon material after optimized in the procedure.

The AlSi10Mg powder was prepared by supersonic gas atomization. After classified, the powder was fabricated into block by selective laser melting (SLM). The microstructure, phase, and evolutions of powder and block were investigated by optical microscope, scanning electron microscope and X-Ray Diffraction. The tensile properties of SLM block were tested by tensile experiments at room temperature. The results show that the size distribution of AlSi10Mg powder after classified can meet the requirements of SLM technology. The powder always is spherical and spherical-like. Meanwhile, the microstructure of powders is fine and uniform, which contain α(Al) matrix and (α+Si) eutectic. In addition, the melt pool boundaries of SLM block are legible. The microstructure is also uniform and densified, the relative density approaches to 99.5%. On the other hand, only α(Al) and few Silicon phase are detected in this condition, due to the most alloying elements are dissolved in α(Al) matrix. At room temperature, the ultimate tensile strength of SLM block reaches up to 442 MPa.

Impinging jet ventilation (IJV), which supplies a high momentum air jet impinging and spreading over the floor, could be used in both cooling and heating modes. However, as a low-level supply system, the excessive temperature difference between head and ankle levels may exist due to the cool air being directly supplied to the occupied zone. As one type of different personalized ventilation (PV) terminal device, ductless personalized ventilation (DPV) is a self-standing system and doesn’t require an extended air duct. In this study, numerical simulation was used to assess the performance of DPV combined with IJV in office buildings under different operating parameters. The results show that a large temperature difference between the occupant’s head and ankle will be significantly decreased by the application of DPV while not influencing the stratification characteristics of impinging jet ventilation.

SARS-Cov-2 has caused enormous damage to society and put human health at a hazardous level. Optimizing air distribution patterns is one of the most useful manners to minimize the infection risk of susceptible individuals. Mixing ventilation is widely used, but the effect of air supply rate on indoor infection probability has not been studied yet. Three air supply rates, including 576, 864 and 1152 m3/h were adopted to study this problem in a simulated room, with dimensions of 5m×5m×2.7m. The Computational Fluid Dynamics (CFD) method was used to consider indoor flow fields under three cases. The infection probability was calculated by the revised Wells-Riley model. The results showed that the overall infection probability decreased as the air supply rate increased. Meanwhile, the infectious air exhaled by the infector would flow along with the supply airflow in a certain direction, resulting in a nonuniform distribution of infection probability in the room. Increasing air supply rate and optimizing workstation layout may be two useful manners to reduce infection probability in mixing ventilation rooms.

In heating model, impinging jet ventilation (IJV) supplies warm air jet with high momentum which impinges and spread over floor. Thermal stratification in opposite direction (temperature of foot area is higher than head area.) is found in the area near supply opening, because high residual momentum of the jet after impinging can resist thermal buoyancy in a considerable distance on floor surface. Negative vertical temperature gradient was seldom explored. To study how negative vertical temperature gradient affects local thermal comfort and work performance, 16 subjects (8 males and 8 females) were asked to work in a room with three negative vertical temperature gradients (1, 3, 5k/m) between head (1.1 m) and ankle levels (0.1 m). In this study, overall thermal sensation, local thermal sensation of body segments and work performance were collected. The results show that work performance and thermal comfort could be improved by higher negative vertical temperature gradients.

Face and neck cooling has been found effective in improving thermal comfort during exercise in the heat despite the fact that the surface area of human face and neck regions accounts for only 5.5% of the entire body. Presently very little documented research has been conducted to investigate cooling the face and neck only to improve indoor thermal comfort. In this study, 16 subjects (8 males and 8 females) used two highly energy efficient wearable face and neck cooling fans to improve occupant thermal comfort in two warm indoor conditions (30 and 32 °C). Results showed that both cooling fans could significantly reduce local skin temperatures at the forehead, face and neck regions. Local thermal sensation votes at the face and neck and the overall thermal sensation votes decreased obviously at 30°C and 32°C. Both cooling fans could raise the acceptable HVAC temperature setpoint to 32.0 °C, which will significantly reduce the energy consumption of HVAC.

Indoor occupant information has an obvious influence on operating parameters of heating ventilation and air conditioning (HVAC) system, which further affects occupants’ thermal comfort and energy consumption. This pilot study proposes an occupant centric control (OCC) strategy for stratum ventilation (SV) to achieve demand control ventilation (DCV). Firstly, the computer vision sensing system and deep learning algorithm are used to detect the number of occupants in real time, and the accuracy of the number of occupants in the office environment was evaluated. Then, the occupant centric stratum ventilation control strategy is designed by the dynamic changes of cooling load. Finally, the thermal comfort and air quality of the thermal environment created by the OCC strategy were evaluated through subject experiment, and the energy consumption of the HVAC system was calculated in combination with the energy consumption simulation software. This study adjusts system setting values according to actual needs, so that the HVAC system responds to the dynamic changes of the indoor cooling load in real time, creating a comfortable and healthy indoor environment in an energy efficient manner.

Underground spaces were paid more attention in the 21st century. As a special underground space, the development of tunnels was even faster. The damage in tunnel, caused by fire and other hazards, is worse than that in spaces above ground due to construction characteristics of underground spaces. Hot smoke cannot be exhausted in time when a fire occurs in tunnel. Therefore, space temperature rises quickly and flashover occurs. Meanwhile, smoke will be accumulated because of poor ventilation. Incomplete combustion, and production of harmful gases such as CO were caused. This review regarding modelling and design methods, based on the characteristics of tunnel fires, summarizes earlier findings and proposes further study plans.

Temporarily occupied space (TOS) is defined as a conditioned space in which most of occupants stay for less than a certain period (e.g., 40 min). Base on the concept of TOS, specific application scenarios for transient and non-uniform thermal environments were explored by chamber tests. In the study, human subjective assessments were obtained from 16 subjects (8 males and 8 females). The synergy effect of temporal and spatial alliesthesia in TOS was quantitatively analyzed, which could achieve energy efficient thermal comfort. The synergy effect extended human thermal comfort under lower neutral temperature.

Intermittent air jet strategy (IAJS) has been proven to provide a satisfactory indoor thermal climate with high energy efficiency in spaces with high occupancy density. Compared with traditional ventilation strategy, IAJS system creates heterogeneous conditions around the occupants, which complicates the relationship between thermal sensation and thermal comfort. The effect of different intermittent cycles on the thermal comfort of occupants needs to be further discussed. In addition, it is necessary to investigate whether IAJS system can play a better role in hot and humid summer conditions in China. Experiments were conducted in a chamber with two rows of seated occupants. Twelve cases were designed, including different combinations of room air temperatures (24°C, 26°C and 28°C) and intermittent period (start 90 s stop 90 s, start 3 min stop 1.5 min, start 1.5 min stop 3 min and start 3 min stop 3 min). Twelve subjects were recruited for subjective investigations. The subjects performed sedentary work and wore summer clothing. Subjective responses to the thermal environments were collected. Wind speed, temperature and CO2 concentration in the occupied area were measured. The results show that IAJS has a potential to be used as a primary ventilation system primary ventilation system such as classrooms in China. When the indoor air was set between 24°C and 26°C, IAJS could create a thermal climate that made the occupants thermally neutral. Additionally, IAJS created an indoor thermal environment acceptable to most occupants, even at a setting temperature of 28 °C.

Radiant floor heating systems provide comfortable indoor thermal environment. Primary air supply systems can be used to remove contaminants in the space heated by radiant floor. In this study, heating performance of integrated system of impinging jet ventilation (IJV) and heating floor was numerically investigated. The lowest floor heating capacity was 0 W/m2 and gradually increased to 50W/m2, and the primary air temperature supplied by IJV were 14, 16 and 18°C, respectively. In terms of contaminant removal efficiency, contaminant removal efficiency (CRE) was applied. The vertical dimensionless temperature distribution was used to analyse the heating performance of HF on supply air. The numerical results showed that the supply air layer of IJV could be heated by 60% to 80% under the heat effect of HF. The same is true for low supply air temperature 14 °C. The integrated system IJV/HF generated the weaken thermal stratification which is beneficial for energy saving. The CRE of IJV/HF system was influenced by the downward airflow of external wall. Sufficient supply air could overcome the downflow and effectively increase the CRE value (> 2).

In the post-COVID-19 era, the market for emergency medical supplies has shrunk, and related production capacity is rapidly overcapacity.The supply chain is at risk of interruption. First, we analyzed the decision-making behavior of supply chain members from the perspective of evolutionary game, and used the probability density function to transform the game model into a sharp mutation model; secondly, we simulated the impact of factors such as cooperative income on catastrophe phenomena; finally, we introduced capacity reserves to advise on the sustainability of emergency supply chains. The results show that: ①There is a set of divergence points in the emergency supply chain system. When the parameter combination is located in the set sum, the system is prone to mutation phenomenon; ②Before the supply chain state changes abruptly, the cooperation income of the supply chain is increased, and the initial cooperation among members is improved. Probability is the main idea to ensure the sustainability of the supply chain; ③Capacity reserves are conducive to stabilizing cooperation among members, but factors such as reserve scale should also be avoided in the collection of divergence points.

Oxygen-enriched combustion can improve thermal efficiency and reduce CO, unburned hydrocarbons and soot emissions in internal combustion engines. There are significant differences in the combustion process and pollutant emissions between oxygen-enriched and air condition. In order to develop an improved understanding of the effect of oxygen concentration on n-heptane oxidation, the jet-stirred reactor oxidation characteristics of n-heptane were experimentally tested at temperatures of 450-950 K and pressures of 1.03 atm with the residence time (τ) of 2 s, under the condition of oxygen mole fractions from 0.055 to 0.6. Meantime, the simulations were performed on CHEMKIN. Results show that, firstly, with the increase of oxygen concentration, the NTC (Negative Temperature Coefficient) effect is weakened, mainly due to the strengthening of low-temperature reaction path, which is also the reason for the improvement of ignition stability in cold-start condition of engines. Secondly, the activity of the reaction system improves with the increase of oxygen concentration. Within 500-750 K, it is due to enhancement of the low-temperature reaction path. When the temperature is higher than 750 K, the improvement is due to the enhancement of decomposition of H2O2 and addition reaction of H and O2. Thirdly, with the increase of oxygen concentration, both the generation and consumption of CO are strengthened, which leads to the tip of the diesel spray flame changing from soot area under air condition to the CO chemiluminescence.

Thermal comfort plays an important role in human life and it affects occupant satisfaction, health, and productivity. Individual differences are not considered in traditional control strategies based on temperature setpoints. The reality is that operators often expend more energy to maintain the indoor environment and the thermal satisfaction of occupancy is not as well as expected. Thus, individual thermal comfort models based on physiological parameters and environmental parameters were presented using the back-propagation (BP) neural network. Moreover, we used three training algorithms including Levenberg-Marquardt (L-M), Bayesian Regularization, and Scaled Conjugate. We observed that using the L-M algorithm resulted in slightly better performance (R=0.96) than other algorithms. The precision results suggest that the BP network algorithm is an effective approach for real-time predicting thermal comfort. In the follow-up study, we would focus on feature engineering (feature selection) and introduce appropriate variables (e.g., heart rate) to improve the model’s accuracy.

This study selects two degree of freedom dynamic model as the research object, and the automatic parking process is analyzed. The longitudinal cascade controller of speed PID and position PID is used to control the longitudinal motion of the vehicle. The lateral tracking controller based on LQR optimal theory is adopted, and the feedforward control is added to form the optimal feedforward LQR controller as the lateral tracking controller. Based on the co-simulation platform of MATLAB/Simulink and CarSim, the function of the designed automatic parking trajectory tracking control strategy is verified. The car test was completed. The ultrasonic sensor, raspberry pie and Arduino were used as the main parts to build an intelligent car test platform to simulate the performance of the designed tracking control strategy in the real vehicle. Software simulation results and vehicle test results showed that the designed control strategy can ensure the path tracking performance of vehicle under normal parking speed, and has good tracking accuracy, real-time performance and vehicle driving stability.

Hedychium putaoense Y.H. Tan & H.B. Ding, a new species of Zingiberaceae from Putao, Kachin state, Northern Myanmar, is described and illustrated. It is similar to H. densiflorum Wall. and H. longipedunculatum A.R.K. Sastry & D.M. Verma, but differs by its very small bract (4–6 × 2.5–3 mm vs. 18–19 × 5–5.5 mm and ca. 11 × 7 mm, respectively), semicircle and dark red bracteole, orange flower and broadly falcate to lanceolate lateral staminodes.

During the early failure of the rolling bearing,the fault signal is very weak and the fault information is difficult to be extracted because of the influence of the background noise,in order to be able to effectively detect the bearing failure. A new diagnosis approach which combines minimum entropy deconvolution（MED） and resonance sparse signal decomposition（RSSD） is put forward. Firstly,the MED is used to reduce noise signal of the bearing fault vibration signal. Then the RSSD is used to decompose the signal into the high resonance component containing the harmonic signal and the low resonance component containing the transient impact signal. Finally,the envelope power spectrum is used to extract the fault characteristic frequency from the low resonant component. Through simulation and experiment,this method is suitable for weak fault feature extraction.

When the roller bearings are in the early stage of failure,the characteristic signal is weak and it is affected by the interference noise,which makes the fault feature difficult to extract. In order to solve this problem,a fault diagnosis method based on the combination of local mean decomposition（ LMD） and maximum correlated kurtosis deconvolution（ MCKD） is proposed. Under the strong noise environment,LMD is difficult to extract the characteristic of weak fault signal,therefore,a set of PF components that are decomposed by LMD which use the correlation coefficient and kurtosis value select sensitive component for signal reconstruction. Then MCKD is used to filter and it is used to highlight the pulse of fault signal. Finally,according to the signal envelope power spectrum,the fault characteristic frequency is extracted,the effectiveness of the method is proved by some simulation and application examples.

Background The Acute Physiology and Chronic Health Evaluation (APACHE) II scoring system and the Sequential Organ Failure Assessment (SOFA) scoring system are widely used for critically ill patients. We evaluated whether APACHE II score and SOFA score predict the outcome for trauma patients in the intensive care unit (ICU). Methods We retrospectively analyzed trauma patients admitted to the ICU in a single trauma center between January 2014 and December 2015. The APACHE II score was figured out based on the data acquired from the first 24 hours of admission; the SOFA score was evaluated based on the first 3 days in the ICU. A total of 241 patients were available for analysis. Injury Severity score, APACHE II score, and SOFA score were evaluated. Results The overall survival rate was 83.4%. The non-survival group had a significantly high APACHE II score (24.1 ± 8.1 vs. 12.3 ± 7.2, P < 0.001) and SOFA score (7.7 ± 1.7 vs. 4.3 ± 1.9, P < 0.001) at admission. SOFA score had the highest areas under the curve (0.904). During the first 3 days, SOFA score remained high in the non-survival group. In the non-survival group, cardiovascular system, neurological system, renal system, and coagulation system scores were significantly higher. Conclusions In ICU trauma patients, both SOFA and APACHE II scores were good predictors of outcome, with the SOFA score being the most effective. In trauma ICU patients, the trauma scoring system should be complemented, recognizing that multi-organ failure is an important factor for mortality.