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The research on the thermal decomposition of propellant is critical to determining its safe storage life. The thermogravimetry (TG) testing of nitramine propellants plasticized by nitroglycerin (NG), glycidyl azide polymer (GAP), 2,2-dinitropropanol hexanoate (DNPH), and N-butyl-2-nitratoethylnitramine (BuNENA) was performed under non-isothermal circumstances. The thermal decomposition mechanism of propellant was then analyzed using the model-fitting method, and the storage life was predicted based on the mechanism. The results show that when heated to the same mass loss, the temperature of GAP-NC-RDX, BuNENA-NC-RDX, and DNPH-NC-RDX is higher than that of NG-NC-RDX. GAP-NC-RDX, BuNENA-NC-RDX, and DNPH-NC-RDX propellants have superior thermal stability to that of NG-NC-RDX. The kinetic mechanism functions and equations of the propellants were calculated, and multi-step reaction models of the thermal decomposition were built. The major thermal decomposition mechanism of nitramine propellants was discovered to be composite autocatalytic decomposition (Kamal-Sourour equation), which means that the reaction of reactants and the reaction catalyzed by products occur in tandem. The decomposition depth of propellants increases as the temperature rises during the same storage time. The storage lifetimes of GAP-NC-RDX, BuNENA-NC-RDX, DNPH-NC-RDX, and NG-NC-RDX propellants at 288 K are 28.71 years, 24.49 years, 18.34 years, and 16.33 years, respectively. The inclusion of GAP, DNPH, and BuNENA in the formulation improves the storage life of propellant more than NG. This study offers an attractive strategy for analyzing the decomposition mechanism of propellant with a multi-step decomposition reaction and forecasting its storage life.

Abstract This network meta-analysis investigated the effects of 8 types of physical exercises on treating positive symptoms, negative symptoms, general psychopathology, and the Positive And Negative Syndrome Scale (PANSS) total score in patients with schizophrenia. The methods adhered to PRISMA guidelines and used the Cochrane risk of bias tool for quality assessment, and Stata software for data analysis. Data were sourced from PubMed, Embase, Web of Science, and the Cochrane database up to August 15, 2023, following PICOS principles. A total of 25 studies including 1441 participants were analyzed. Results showed that resistance exercise seems to be effective for improving positive symptoms, while Yoga was more effective for negative symptoms. Low-intensity aerobic exercise was optimal for general psychopathology, and Yoga was effective in improving the PANSS total score. The study concluded that yoga and aerobic exercise demonstrated superior performance, but the impact of exercise on patients with schizophrenia is also influenced by individual factors and intervention dosages. Therefore, a pre-assessment of patients considering factors such as interests, hobbies, and physical capabilities is crucial for selecting appropriate exercise modalities.

The Anthropocene era is characterized by the escalating impact of human activities on the environment, as well as the increasingly complex interactions among various components of the Earth system. These factors greatly affect the Earth’s evolutionary trajectory. Despite notable strides in sustainable development practices worldwide, it remains unclear to what extent we have achieved Earth sustainability. Consequently, there is a pressing need to enhance conceptual and methodological frameworks to measure sustainability progress accurately. To address this need, we developed an Earth Vitality Framework that aids in tracking the Earth sustainability progress by considering interactions between spheres, recognizing the equal relationship between humans and nature, and presenting a threshold scheme for all measures. We applied this framework at global and national scales to demonstrate its usefulness. Our findings reveal that the current Earth Vitality Index is 63.74, indicating that the Earth is in a “weak” vitality. Irrational social institutions, unsatisfactory life experiences and the poor state of the biosphere and hydrosphere have remarkably affected the Earth vitality. Additionally, inequality exists between high-income and low-income countries. Although most of the former exhibit poor human-nature interaction, all of them enjoy good human well-being, while the opposite is true for the latter. Finally, we summarize the challenges and possible options for enhancing the Earth vitality in terms of coping with spillover effects, tipping cascades, feedback, and heterogeneity.

The severe erosion and inadequate mechanical strength are prominent challenges for high-energy gun propellants. To address it, novel PTW@PDA composites was prepared by polydopamine(PDA)-modifying onto potassium titanate whisker(PTW, K2Ti6O13), and after was incorporated into gun propellant as erosion-reducing and mechanical-reinforcing fillers. The interfacial characterizations results indicated that as-prepared PTW@PDA composites exhibits an enhanced surface compatible with propellant matrix, thereby facilitating their dispersion into propellants more effectively than raw PTW materials. Compared to original propellants, PTW@PDA-modified propellants exhibited significant less erosion, with a Ti–K-based protective coating being detected on the eroded steel. And 0.5 wt% and 1.0 wt% addition of PTW@PDA significantly improved impact, compressive and tensile strength of propellants. Despite the inevitably reduction in relative force, PTW@PDA slightly increase propellant burning rate while exerting little adverse impact on propellant dynamic activity. This strategy can provide a promising alternative to develop high-energy gun propellant with less erosion and more mechanical strength.

BackgroundAlthough social capital has been linked to dietary intake particularly in disadvantaged populations, little is known about the mechanisms. This study aimed to investigate whether social support (SS) and nutrition knowledge (NK) mediate the association between social capital and healthy eating habits.MethodsA probability sample of two ethnic minority groups in Yunnan Province, Southwest China were included (n = 1,033, mean age 47.5 ± 14.7 years). Bonding and bridging social capital (BOC and BRC) were assessed with the Personal Social Capital Scale (PSCS-16). Dietary data were evaluated with the Chinese Healthy Eating Index (CHEI), a measure of diet quality which reflects adherence to the Chinese Dietary Guidelines. NK and SS were measured with a validated questionnaire and scale, respectively. Structural Equation Modeling was used to calculate the direct, indirect and total effects of social capital on CHEI scores.ResultsThe mean score of CHEI was 57.4 ± 9.8, which was significantly lower in men and older people. Low adherence to dietary guidelines were to observed in the consumption of dairy, beans, nuts, animal-source food vegetables and fruits. BOC and BRC were positively associated with CHEI score (β = 0.37 and 0.38, all p

Energetic plasticizers are an essential component of propellants and have a significant impact on their performance, such as energy, combustion, and mechanics. Therefore, there is significant practical value in understanding how plasticizers affect the performance of propellants. In this work, the glass transition temperatures of several energetic plasticizers were compared. By adding energetic plasticizers with good compatibility with the propellant and a low glass transition temperature to the propellant, nitramine gun propellants containing different energetic plasticizers were prepared through a semi-solvent method. The compatibility, thermal behavior, phase structure, composition, mechanical properties, energy, and combustion performance of the nitramine gun propellants were characterized. The influence of plasticizers on the phase structure of the propellant and its mechanism on the combustion performance of the propellant were discussed. Energetic plasticizers GAPE, DNPH, and BuNENA have good compatibility and chemical stability with NC-RDX and display good plasticization. GAPE–NC–RDX, DNPH–NC–RDX, and BuNENA–NC–RDX propellants exhibit stable combustion performance at −40 °C, 20 °C, and 50 °C. Compared with the nitramine gun propellant plasticized with NG, the impact strength of the propellant plasticized with DNPH and BuNENA increased by 108.1 % and 17.2 % at −40 °C, respectively. This work offers a solution to improve the phase structure, mechanical properties, and combustion stability of heterogeneous gun propellants and provides a way to suppress the excessive burning rate and flame temperature of propellants.

A mixed nitrate ester propellant composed of nitrocellulose, nitroglycerin, triethylene glycol dinitrate, and dendrimer DP-2 was studied to explore the effects of DP-2 on the rheological properties of the propellant during the solventless extrusion process. The results showed that the apparent shear viscosity of the propellant decreased gradually with the increased mass fraction of the DP-2 from 0 wt% to 2 wt%. Additionally, it was evident that the inclusion of 0.5 wt% DP-2 leads to a notable decrease in both the apparent shear viscosity of the propellant and the torque of screw by over 50%. However, in contrast to the change in fluidity observed from 0 wt% to 0.5 wt%, the enhancement trend of propellant fluidity becomes less significant as the DP-2 content continues to increase. The effects of DP-2 on thermal properties, chemical stability, mechanical sensitivity, mechanical property, and combustion behavior of the propellant were comprehensively assessed. The results demonstrated that DP-2 exhibited promising potential as a flow modification additive for the manufacture of the propellant by solventless extrusion process.

Single-based propellants containing 0.4 wt%, 0.8 wt% and 1.6 wt% nickel powders(NPs) were prepared and investigated in closed bomb tester and transparent combustion chamber, which can provide variable-pressure and constant-pressure conditions for propellant burning, respectively. In closed bomb tester, propellants burned to a pressure above 5–220 MPa. The results showed that burning rate of propellants was increased by 19.0 %, 12.5 % and 11.9 % in 5–8 MPa, 8–16 MPa and 20–200 MPa, when 1.6 wt% NPs used in propellant. Meanwhile, propellants burning in combustion chamber were with a constant pressure of 1.0 MPa, 1.5 MPa, 2.0 MPa, 3.0 MPa and 5.0 MPa. The burning rate of propellants can be increased by NPs in 1.0–5.0 MPa. While the catalytic efficiency(Z) had high dependence on NPs contents and burning pressure. At 5.0 MPa, 0.4 wt%, 0.8 wt% and 1.6 wt% of NPs enhanced burning rate of propellants by 42 %, 44 % and 68 % than that of original propellants. In pressure below 3.0 MPa, burning rate of propellants cannot be increased with 0.4 wt% and 0.8 wt% NPs, but that can be enhanced with 1.6 wt% NPs, suggested that higher NPs content and higher pressure were conducive to catalytic effect, which was significant with the pressure above 5 MPa. Furthermore, after NPs incorporating into propellant, the distance from flame zone to propellant burning surface was significantly reduced. And the potential catalytic mechanism was proposed.

Abstract In the preparation of the slurry in the slurry shield (SSS) and subsequent reduction of the waste slurry produced by the slurry shield (WSSS), the additives in SSS improve the quality of filtration cake on the excavation surface, but they may also remain in WSSS, which have a negative impact on the reduction efficiency of WSSS. Therefore, it is valuable to establish the relationship between SSS and WSSS with additives as a link. Given this, this paper prepared WSSS with different dosages of additives and studied the influence of residual additives on the reduction. The residual additives made the reduction efficiency of WSSS worse, and the specific resistance to filtration increased by one to two orders of magnitude. The residual additives change the content of bound water or reduce the available sites of the soil particles that can be adsorbed by flocculants, leading to worse reduction results. To reduce the difficulty of reduction, combining polymer and bentonite as additives are recommended to prepare SSS. Polyaluminium chloride (PAC) acts by reducing bound water content through the interaction with residual bentonite, simultaneously augmenting PAM flocculation, which is recommended for reducing WSSS. This paper provides a reference for selecting materials used to prepare SSS and the subsequent reduction of WSSS.

Nitroguanidine (NQ) in solvent-based triple-base propellants (STP) has a propensity to peel off and detach from the matrix, leading to significant defects, such as interface debonding within the propellant’s microstructure. This ultimately results in reduced and unstable mechanical properties. To address this critical issue, an efficient and eco-friendly manufacturing process was employed to successfully produce solventless triple-base propellants (SLTPs) as a comparison to conventional STPs. SLTP samples exhibit a mutually supportive three-dimensional spatial structure, with NQ crystals within the propellant matrix more securely bonded to the interface. They also demonstrate higher relative density (1.68 g·cm−3), more stable molding dimensions (no contraction), and enhanced tensile strength (41.92 MPa). Quasi-static structural failure tests reveal that the standard deviation of compressive strength for SLTP samples in three axes is smaller, registering at 1.10. The dynamic structural damage performance analysis indicates that the failure of energetic composite materials is attributable to separation fracture damage after the appearance of cracks on the tensile surface at −40 and 25 °C. Furthermore, the structural failure of these materials occurs due to significant collapse failure after the compression surface bends inward at 50 °C. Consequently, the present study offers a reliable theoretical foundation and procedural strategy for enhancing the structural strength of triple-base propellants.

To ensure the reliability of the Wireless Power Transfer (WPT), the simultaneous wireless power and data transmission technology has gained more attention to realize real-time information exchange between the transmitter and receiver sides. In this paper, the shared channel technology and 2FSK modulation method are proposed to accomplish data and power transmission simultaneously. The theoretical analysis of the series-series compensation network is established, and the data modulation method through frequency-shifted modulation is analyzed. In order to reduce the bit error rate of transmitted data, a communication data format containing start and stop bits is proposed in this proposed system. Finally, an experimental prototype is constructed to validate the correctness and effectiveness of the proposed design and approach.

Abstract Background In view of the fact that there is no effective treatment for dementia, the number of years that dementia patients have to live with dementia will gradually increase for the rest of their lives, and the disability loss caused by dementia will increase. It is urgent to study the influence of risk factors on dementia by making use of the potential of prevention. The purpose of this study is to quantify the burden of dementia disability attributable to risk factors by assessing the population attributable fractions (PAFs) in Jiangxi Province, which is one of the regions of moderate aging process of China. Methods The prevalence data of nine risk factors were obtained through the Sixth National Health Service Survey in 2018, which covered 2713 older people. Levin’s formula was used to calculate the PAF for each risk factor for dementia. We adjusted the PAF for communality between risk factors, and used these values to calculate overall weighted PAFs and the years lived with disability (YLDs), which were attributable to nine risk factors. Results The number of dementia cases and their proportions that can theoretically be prevented by nine identified risk factors were 111636 (99595-120877) and 66.8% (59.6-72.3), respectively. The total YLDs of dementia were estimated to be 61136 (46463-78369) (males: 36434 [24100-49330], females: 23956 [14716-34589]). Physical inactivity (11639 [8845-14920]), low social contact (9324 [7086-11952]), and hearing loss (5668 [4307-7265] were the top three contributors to dementia. Conclusions The moderate aging areas represented by Jiangxi Province have great potential in the prevention of dementia. Targeted interventions and management of risk factors can effectively reduce the disability burden of dementia.

With the continuous utilization of renewable energy, the number of onshore wind turbines is increasing. Small design improvements can save costs and facilitate the maintenance and repair of the wind turbine foundation. In this paper, an existing gravity expansion foundation with an anchor cage is improved. Our improvements further expand the space inside the foundation and reduce the length of the anchor bolt, which could reduce the costs and facilitate construction. To study the performance of the new foundation, a three-dimensional finite element model of the foundation–soil–anchor bolt was established via a finite element simulation. The damage evolution of the foundation was simulated with the concrete damage plasticity model (CDP). The separation ratio, foundation settlement, inclination ratio, reinforcement stress, foundation stress, and foundation damage of the new foundation under ultimate load conditions were analyzed. The influence of parameters h1 and b3 on the performance of the foundation was further studied. The finite element analysis results show that the tensile stress of concrete can be effectively reduced by appropriately increasing the corbel height and ring beam width of the foundation. The results also show that the improved wind turbine foundation force is reasonable and can meet the use of the actual project requirements on the level of finite element analysis.

Foodborne bongkrekic acid (BA) poisoning is a fatal foodborne disease in China. From 2010-2020, a total of 19 BA poisoning outbreaks were reported to the China National Foodborne Disease Outbreak Surveillance System. These outbreaks involved 146 illnesses, 139 hospitalizations, and 43 deaths, with a case-fatality rate of 29.5%. Approximately 73.3% of the outbreaks occurred in South and Southwest China. Homemade fermented corn flour products, tremella, and sweet potato flour and corn flour products (jelly) caused more early outbreaks, and novel vehicles (wet rice noodles and Auricularia auricula) were associated with later outbreaks in the study period. Outbreaks most frequently occurred at home (79.0%) and in restaurants (21.0%). The prohibition of traditional processed homemade fermented corn flour products and improvement in bongkrekic acid poisoning case identification and early treatment have resulted in a reduction in the case-fatality rate.

Abstract Rock mass condition assessment during tunnel excavation is a critical step for the intelligent control of tunnel boring machine (TBM). To address this and achieve automatic detection, a visual assessment system is installed to the TBM and a lager in-situ rock mass image dataset is collected from the water conveyance channel project. The rock mass condition assessment task is transformed into a fine-grain classification task. To fulfill the task, a self-convolution based attention fusion network (SAFN) is designed in this paper. The core of our method is the discovery and fusion of the object attention map within a deep neural network. The network consists of two novel modules, the self-convolution based attention extractor (SAE) module and the self-convolution based attention pooling algorithm (SAP) module. The former is designed to detect the intact rock regions generating the attention map, and the latter is designed to improve the performance of classifier by fusing the attention map that focuses on the intact rock regions. The results of SAFN are evaluated from aspects of interpretability, ablation, accuracy and cross-validation, and it outperforms state-of-the-art models in the rock mass assessment dataset. Furthermore, the dynamic filed test show that our assessment system based on the SAFN model is accurate and efficient for automated classification of rock mass.

BackgroundAsthma is a major global health challenge. The global strategic management and prevention of asthma report has been published, but health system planning for asthma requires a careful assessment of asthma epidemiology. This study described the incidence and mortality of global asthma from 1990 to 2019.MethodsBased on data from the global burden of disease study (GBD) 2019, we present spatial and temporal trends in asthma incidence and mortality for the world and its 204 countries and territories from 1990 to 2019. Meanwhile, age-period-cohort analysis was used to explore factors influencing asthma incidence and mortality.ResultsFrom 1990 to 2019, the incidence of asthma decreased from 601.20 per 1,00,000 to 477.92 per 1,00,000, and the mortality of asthma decreased from 8.60 per 1,00,000 to 5.96 per 1,00,000. High sociodemographic index (SDI) areas have higher age-standardised asthma incidence and low sociodemographic index areas have higher age-standardised asthma mortality. The age-period-cohort analysis results showed that the relative risk (RR) of incidence was high in children and the RR of mortality was high in elderly individuals. The RR of both asthma incidence and mortality showed a decreasing trend over time. The RR of asthma incidence in the recent birth cohort was higher than that in the previous birth cohort. The RR of asthma mortality continued to decline with the change in the birth cohort.ConclusionsGlobal asthma incidence and mortality decreased from 1990 to 2019. The decline in asthma incidence was mainly attributed to age effects and period effects, and the decline in asthma mortality was mainly attributed to period effects and cohort effects. Focusing on the risk of incidence in children and the risk of mortality in the elderly, promoting healthy lifestyles and controlling environmental risk factors can help to better control asthma.

Abstract Background Social support is an important health determinant and may affect dietary behaviors. The purpose of this study was to examine the relations between perceived social support and the Chinese Diet Balance Index-16 (DBI-16) among ethnic minority groups in Southwest China. Methods This cross-sectional study was conducted between May 2019 and August 2020 among six ethnic minority groups native to Yunnan Province (n = 3564). Perceived social support from family, friends and significant others were measured with the Multi-dimensional Scale of Perceived Social Support (MSPSS). Dietary data were obtained using a 100-item Food Frequency Questionnaire (FFQ) and a lifestyle questionnaire. Lower Bound Score (LBS), Higher Bound Score (HBS) and Diet Quality Distance (DQD) which represent inadequate, excessive and unbalanced food intake respectively were calculated to measure the compliance with the recommendations of the Dietary Guidelines for Chinese 2016. Results One thousand four hundred ninety-six men and two thousand sixty-eight women were included. 51.2% of the subjects had moderate or high levels of inadequate intake; 21.3% had moderate or high levels of excessive intake; and 74.0% had moderate or high levels of unbalanced dietary intake. With potential confounders adjusted, support from family was negatively associated with inadequate intake, while support from friends was positively associated with inadequate and excessive intake. No significant associations were found between perceived social support from significant others and diet quality indicators. Conclusions An unbalanced diet is common among adults of the ethnic minority groups in Yunnan Province, Southwest China. Social support should be taken into account in designing nutrition interventions rather than focusing solely on individuals.

The electric unmanned aerial vehicles (UAVs) are rapidly growing due to their abilities to perform some difficult or dangerous tasks as well as many public services including real-time monitoring, wireless coverage, search and rescue, wildlife surveys, and precision agriculture. However, the electrochemical power supply system of UAV is a critical issue in terms of its energy/power densities and lifetime for service endurance. In this paper, the current power supply systems used in UAVs are comprehensively reviewed and analyzed on the existing power configurations and the energy management systems. It is identified that a single type of electrochemical power source is not enough to support a UAV to achieve a long-haul flight; hence, a hybrid power system architecture is necessary. To make use of the advantages of each type of power source to increase the endurance and achieve good performance of the UAVs, the hybrid systems containing two or three types of power sources (fuel cell, battery, solar cell, and supercapacitor,) have to be developed. In this regard, the selection of an appropriate hybrid power structure with the optimized energy management system is critical for the efficient operation of a UAV. It is found that the data-driven models with artificial intelligence (AI) are promising in intelligent energy management. This paper can provide insights and guidelines for future research and development into the design and fabrication of the advanced UAV power systems.

The wireless power transmission (WPT) system for electric vehicle charging has the advantages of being safe and reliable, without plugging and unplugging, but the random misalignment between the energy transmitting coil and the energy receiving coil will cause uncertain disturbance to the transmission power and system performance. Therefore, it is necessary to improve the robustness of the wireless power transmission system. This paper designs a TUBE model predictive control (TMPC) to make the system converge to the desired value along the reference trajectory. To reduce the difficulty of solving the reference trajectory, the idea of segmented optimization is adopted. State feedback is presented to further enhance the system’s anti-disturbance ability to increase the system transmission power. Moreover, the compensation for the sampling delay of the controller is proposed to ensure the stability of the control system. Experimental results demonstrate that, compared with traditional predictive control, the proposed TUBE MPC based on state feedback control strategy can increase the transmission power of the system by about 10% under uncertain misalignment.

AbstractThere are 1,000 geothermal wells with depths of 1500–2000 m drilled into the upper Tertiary sandstone geothermal reservoir in the Guantao Formation in the North Shandong Plain, which support about 61 million square meters of domestic space heating. Concerning the large-scale exploitation of the Guantao Formation geothermal reservoir and its important role in clean space heating, it is essential to fully understand the characteristics of the geotemperature, geothermal water flow, and hydrochemical features, especially the heat accumulation and geothermal water enrichment mechanism. Based on the data from pumping tests, temperature logging, water level measurements, and hydrochemistry and isotope sampling and analysis, in this study, the heat sources and accumulation, water sources, and enrichment mechanism of the sandstone geothermal reservoir in the Guantao Formation were explored. The geothermal gradient of the cap rocks and the reservoir’s temperature revealed that the geothermal temperature fields are controlled by fault structures, and the relative high temperature zones are distributed in the area where the uplifts and deep heat-controlled faults converge. The geothermal water-rich area is located in the ancient river channel zone. The closer the water-rich area is to the ancient river channel belt, the deeper and coarser the buried conglomerate aquifer is, and the better the water-rich condition is. The best water-rich areas are found in the alluvial fan of the ancient channel belt.

Stretchable flexible conductive polymer composites (flexible electrodes) had become a research hot spot. In this paper, two-component room-temperature vulcanized liquid silicone rubber (LRTV) and short carbon fibers (CFs) were mixed by mechanical blending without solvent to prepare a tensile self-reply composites with high conductivity. The relationships between the average length, length distribution and content of CFs and the performance of CFs/LRTV composites were investigated. When the CFs length was 100 μ m, the composites achieved a high conductivity. The composites conductivity threshold was reached when the CFs content was 3 wt%. In addition, the composites could be used as a conductor to light the bulb when the CFs content reached 8 wt%. The conductivity remained stable during cyclic stretching with a strain of 8%. The breaking and reconstruction of the internal 3D conductive network in the composites during the stretching process were discovered. The obtained results revealed that CFs/LRTV composites can be used as highly effective, flexible, stretchable electrode materials for stretchable displays, electronic skin, personalized healthcare.

The push-plate kiln is a kind of kiln equipment widely used in the oxygen-free sintering of high-temperature alloy materials. Its flow field monitoring has an important application value for the manufacturing industry. However, traditional simulation methods cannot meet the requirements of real-time applications due to the high computational cost and being time-consuming. The rapid development of artificial intelligence technology will empower the traditional manufacturing industry. In this paper, we propose a data-driven digital twin framework for real-time flow field prediction by combining the CFD modeling simulation, IoT, and deep learning technologies. The framework integrates geometric, rule, physical, and neural network models to achieve the real-time simulation of physical and twin objects. The proper orthogonal decomposition (POD) and multiscale convolutional neural network (MCNN) are innovatively embedded into the framework. The POD is used to map high-dimensional data to low-dimensional features, and the MCNN is used to construct models predicting low-dimensional features for fast flow field prediction. The effectiveness of the proposed model is verified by the push-plate kiln case. The results show that the digital twin can quickly predict multi-physics fields based on the perceptual data to achieve the real-time evaluation of the operating state of the push-plate kiln.

Dezhou City is located in northwestern Shandong Province, China, and is rich in geothermal resources. Approximately 30% of the geothermal wells and geothermal heating areas of Shandong Province are located in Dezhou. A doublet-well layout geothermal system was completed by the Lubei Geo-engineering Exploration Institute for local winter heating, which has been in operation for 4 years. The wellbores penetrated the Guantao Formation with a well spacing of 180 m. This study aims to assess the heat extraction performance of the current well layout and predict the temperature evolution and lifespan. Furthermore, larger well spacing schemes were used in a simulation to test the heat supply potential and sustainability. In this study, the thermal conductivity and permeability were calibrated using in situ measured data from a field production test. A relatively high permeability layer was found between the depths of 1468 and 1536 m. The temperature remained stable in the first 6 years and then started to decrease. The recharging (injection) water tended to concentrate along the bottom highly permeable layer and accounted for over 64% of the outflow in the 100th year of the simulation test. The outflow temperature decreased from 53.9°C to 50°C in the 32nd year, making it less viable for subsequent sustainable exploitation. Hence, a larger well spacing is required for long-term operation based on the same geothermal reservoir. It was found that a spacing of 400 m could guarantee an outflow temperature above 50°C over a 100-year lifespan with an 80 m 3 /h pumping (production) rate. Moreover, the sustainability of the 600-m spacing was almost 2.5 times that of the 400 m case. The modeling and analysis method can be useful for the development and optimization of a doublet-well geothermal system under similar conditions.

Dihydroxylammonium 5,5′-bistetrazole-1,1′-diolate (TKX-50) and nitrocellulose/nitroglycerine (NC/NG) possess good energy properties, which were widely used in propellants, explosives and pyrotechnics. They are easy to contact with each other during their application and storage. However, their thermal characteristics under continuous heat flow have not been reported yet. Therefore, it is of great practical significance to study the thermal properties of TKX-50/NC/NG (mixture of TKX-50 and NC/NG). In this paper, the thermal characteristics and pressure behaviors of TKX-50/NC/NG, TKX-50 and NC/NG were characterized by high pressure differential scanning calorimetry (HPDSC) and adiabatic scanning calorimetry (ASC). The results showed that TKX-50 and NC/NG can promote each other to decompose under continuous heat flow, especially the thermal decomposition which affected by gases generation and heat feedback was more violent in the confined space. The decomposition peak temperature of TKX-50/NC/NG shifted to low temperature when the heat loss was ignored and the removal of decomposition gas was suppressed. The possible decomposition mechanism of TKX-50/NC/NG was speculated. It was considered that the intermediate products of TKX-50 and NC/NG decomposition under thermal stimulation would react with each other, which promoted TKX-50/NC/NG decomposition in one step at lower temperature. Thus, TKX-50 has high reactivity and high potential risk after contact with NC/NG under continuous heat flow. TKX-50 is not suitable for application with NC/NG. This study provides a reference for the structural design of nitrogen rich explosives and further broadens the researchers’ understanding of the application of TKX-50.

Tailless aircraft suffers from limited yaw control power and poor directional stability inherently. To address these issues in the early design process of a tailless configuration with low costs and risks, this paper presents an innovative experimental approach to control law validation and quantitative flying quality evaluation with a dynamically scaled model mounted on a three degree-of-freedom rig in the wind tunnel. The motion equations of the tailless demonstrator on the rig are derived, and then the comparisons of the lateral-directional flight dynamics between the rig constrained model and the free flight model are carried out. Construction of the control augmentation system for yaw and roll motion is accomplished according to the scale modified criteria of flying qualities. Effectiveness of the designed control law is demonstrated with steady pilot-in-the-loop flights at different airspeeds and angles of attack. The achieved closed-loop flying qualities are evaluated by applying multistep maneuvers for low order equivalent system identification. Whereas severe instability is observed in yaw for the open-loop case, the closed-loop flying quality of the Dutch-roll mode can be improved to level 1 at low angle of attack.

Geothermal energy is a clean and environmentally friendly energy source that can be used sustainably; however, attention towards geothermal energy has been intermittent during the last 40 years as a function of the crisis of oil price. However, geothermal reinjection and clogging has been a challenge limiting geothermal development and utilization. In China, widely distributed sandstone geothermal reservoirs have reduced production due to technical constraints such as excessive reinjection pressure and blockage. In this paper, we took the Binzhou sandstone geothermal field in North China as an example and conducted displacement experiments under different temperature and flow rate conditions by collecting in situ geothermal fluid and core rock to obtain changes in sandstone permeability. By comparing the variation in geochemical and mineral composition of geothermal fluids and cores before and after the experiments, combined with a water–rock interaction simulation, we investigated the reasons for the changes in permeability and porosity. The results show that high temperature and low flow rate have relatively minimal displacement pressure, and a flow rate of 1.0 mL/min at 45 °C shows a minimal effect on permeability, while 1.0 mL/min at 55 °C and 0.5 mL/min at 45 °C show a minimal effect on porosity. Flow rate is the main factor controlling permeability, while temperature demonstrated a relatively minor effect. The shift in permeability and porosity is mainly caused by the precipitation of quartz and the conversion of albite to montmorillonite. The injection of fluids at 55 °C may have dissolved additional minerals with a minimal change in porosity. However, the permeability reduction at 55 °C is greater than that at 45 °C, indicating that the blockage, which led to the permeability reduction, contains multiple causes, such as chemical and physical blockages. From the laboratory studies, we recommended that reinjected geothermal water be cooled or kept below the reservoir temperature before reinjection and at moderate flow conditions.

Graphene oxide/carbon nanotube aerogel (GOCA) with honeycomb three-dimensional framework is an ideal reinforcement material which can significantly improve the dispersion in the polymer matrix, and enhance the mechanical properties, thermal and electrical conductivity of the composites. In this work, large-size GOCA and GOCA/polystyrene (GOCA/PS) composite sheet were prepared via critical drying and in-situ polymerization, respectively, and the standard splines of mechanical properties were tested. The results indicated that the tensile, flexural, compressive, and impact strengths of GOCA/PS composites increased with the increase of GOCA content. When the GOCA content was 1.1 wt %, the above mechanical properties increased to the maximum, increased by 103.29%, 60.30%, 177.03%, and 611.38%, respectively. However, as the content of GOCA increased, the electrical conductivity and thermal conductivity showed an increasing trend. In addition, the synergistic enhancement mechanism between GO and CNTs has also been studied. We believe that the present method may provide an effective route for the design and investigation of reinforced composites.

Geothermal reinjection is a new method of geothermal development which can maintain regional geothermal reservoir pressure, and it is conducive to the sustainable development and utilization of geothermal heat. However, geothermal reinjection blockage has always been a problem that restricts geothermal development and utilization, causing geothermal reservoirs, especially the attenuation of sandstone geothermal reservoirs. Considering an example of a typical sandstone geothermal reservoir in Binzhou, in this study, in situ geothermal fluids and borehole cores were collected to conduct automatic rotary reactor experiments under different temperature and acidification conditions in laboratory studies. The chemical compositions of geothermal fluids and core samples before and after the experiment were compared. The results show that both temperature and acid have significant effects on the water–rock interaction. The effect of temperature is mainly shown on mineral solubility, while the effect of acidification is shown in the increased dissolution of calcite and feldspar minerals. Compared with high temperature (65 °C) reinjection conditions, the calcite precipitation at a low temperature (45 °C) is largely reduced, but with larger total mineral volume changes, mainly due to the formation of montmorillonite. Therefore, from the laboratory studies, it is recommended to preform reinjection using a low-temperature fluid, without adding acids.

Abstract Posture adjustment of open-type hard rock tunnel boring machine (TBM) can be achieved by properly adjusting the hydraulic pressure of gripper cylinder and torque cylinders. However, the time-varying inhomogeneous load acting on tunneling face of TBM and complex stratum working condition can cause the trajectory deviation. In this paper, the position and posture rectification kinematics and dynamics models of TBM have been established in order to track the trajectory. Moreover, there are uncertain parameters and uncertain loads from complex working conditions in the dynamic model. An indirect adaptive robust control strategy is applied to achieve precise position and posture trajectory tracking control. Simulation results show when the position deviation only occurs in Y-axis and the current orientation is parallel with the designed axis, the deviation can be corrected by controlling the pressure of gripper cylinder and the actual trajectory meets the designed axis when TBM is pushed forward 0.14 m in X-axis. If the deviation only occurs in Z-axis, then the deviation can be corrected by controlling torque cylinders. If the position deviation occurs both in Y-axis and Z-axis at the same time, the pressure of gripper cylinder and torque cylinders should be controlled at the same time to rectify the deviation. Simulation results are shown to illustrate the effectiveness and robustness of the proposed controller. This research proposes an indirect adaptive robust controller that can track the planned tracking trajectory smoothly and rapidly.

Background: Globalization has brought about rapid economic and technological development, and life expectancy (LE) is constantly increasing. However, it is not clear whether an increase in LE will result in an increase in healthy life expectancy (HLE). This study evaluates trends in the self-rated healthy life expectancy (SRHLE) of residents aged 15 and older in Jiangxi Province of China from 2013 to 2018 and analyzes gender differences and urban–rural differences. This study provides a basis for the formulation of relevant public health policies.Methods: Based on two National Health Services Survey databases of Jiangxi in 2013 and 2018 as well as infant mortality rates and under-5 mortality rates from the Health Commission of Jiangxi, the Sullivan method was used to calculate SRHLE. The changes in SRHLE were decomposed into health and mortality effects using the decomposition method.Results: SRHLE decreased from 56.55 to 55.54 years and from 60.00 to 57.87 years for men and women aged 15 from 2013 to 2018, respectively. The SRHLE of women aged 15 was 3.45 and 2.34 years longer than that of men in 2013 and 2018, respectively. The SRHLE of urban men aged 15 was 2.9 and 4.46 years longer than that of rural men in 2013 and 2018, respectively, and that of urban women aged 15 was 3.28 and 5.57 years longer than that of rural women.Conclusions: The decreased SRHLE indicated that the self-rated health (SRH) status of residents in Jiangxi has worsened, and it provided evidence for the expansion of morbidity, mainly due to the increased prevalence of chronic diseases and the improvement in residents' health awareness. Policy efforts are necessary to control the increased morbidity of chronic diseases and reduce gender and urban–rural differences in the quantity and quality of years lived.

BackgroundFew studies have focused on the influencing factors of dietary practices among ethnic minority groups in China, particularly from a social capital perspective.MethodsBetween May and September 2019, we conducted a cross-sectional survey among adults (n = 1,813) from three ethnic minority communities (A Chang, De Ang and Jing Po) in Yunnan Province, Southwest China. Dietary intakes during the past 12 months were measured with a 100-item Food Frequency Questionnaire (FFQ), and two forms of social capital (bonding and bridging) were measured using the validated Personal Social Capital Scale 16 (PSCS-16). Principal component factor analysis was used to derive dietary patterns from 20 food groups. Multivariate linear regressions were used to examine the associations between social capital and dietary patterns.ResultsTwo distinct dietary patterns were identified: the traditional and the modern. The traditional pattern was characterized by high consumptions of tubers, poultry, rice, fruits, vegetables and low consumptions of oil and salt, whereas the modern pattern was highly correlated with egg, nut, beverage, snack and oil consumptions. After adjusted for potential confounders, the modern pattern was positively associated with bonding capital (β = 0.066; 95%CI: 0.058, 0.075) and negatively associated with bridging capital (β = -0.017; 95%CI: -0.024, -0.010).ConclusionIn conclusion, an unhealthy dietary pattern was identified among the ethnic minority groups in Southwest China. The influences of people's social connections on dietary behaviors should be considered in designing and implementing nutrition intervention programs for the population.

A dwarf, multi-pistil and male sterile dms mutant was previously reported by us. However, the genetic changes in this dms are unclear. To examine the genetic changes, single nucleotide polymorphism (SNP) association, chromosome counting, and high-resolution chromosome fluorescence in situ hybridization (FISH) techniques were employed. By comparing tall plants (T) with dwarf plants (D) in the offspring of dms mutant plants, SNP association analysis indicated that most SNPs were on chromosome 2A. There were three types in offspring of dms plants, with 42, 41 and 40 chromosomes respectively. High-resolution chromosome painting analysis demonstrated that T plants had all 42 wheat chromosomes; the medium plants (M) had 41 chromosomes, lacking one chromosome 2A; while D plants had 40 wheat chromosomes, and lacked both 2A chromosomes. These data demonstrated that dms resulted from a loss of chromosome 2A. We identified 23 genes on chromosome 2A which might be involved in the development of stamens or pollen grains. These results lay a solid foundation for further analysis of the molecular mechanisms of wheat male sterility. Because D plants can be used as a female parent to cross with other wheat genotypes, dms is a unique germplasm for any functional study of chromosome 2A and wheat breeding specifically targeting genes on 2A.

Breastfeeding has a wide range of benefits for both infants and mothers. The identification of factors associated with exclusive breastfeeding (EBF) are important to increase the prevalence of EBF. The study aimed to determine the prevalence of EBF within the first six months and its associated factors in Kaiyuan, Yunnan Province, Southwest China. This cross-sectional study was conducted in Kaiyuan, a middle-sized city of Yunnan Province, Southwest China. Mothers of infants under twelve months were randomly selected for a face to face interview in four towns (two in urban areas and two in rural areas) in Kaiyuan. A structured questionnaire was applied for collection of sociodemographic information, mothers' and infants' health, and breastfeeding information. A 24-hour food recall survey was used to collect infant feeding information. A logistic regression analysis was performed to identify the factors independently associated with exclusive breastfeeding for infants up to six months of age. The number of 417 mothers with infants under six months was interviewed. The prevalence of EBF at six months was 27.34%. Logistic regression indicated that EBF within six months was more likely to be practiced by mothers who had higher average household income per year (OR = 2.09, 95% CI: 1.05-4.17 p = 0.037; OR = 1.85, 95% CI: 1.04-3.28 p = 0.037), and mothers who received breastfeeding information (OR = 2.46, (95%CI: 1.45-4.18, p = 0.0009). The prevalence of EBF in Kaiyuan, Southwest China is considerably lower than national and international recommendations. Yearly household income, and mothers who received breastfeeding information are associated with higher EBF prevalence. Breastfeeding information should be given to mothers in order to increase the prevalence of EBF.

This paper focuses on the design of a disturbance rejection controller for a tailless aircraft based on the technique of nonlinear dynamic inversion (NDI). The tailless aircraft model mounted on a three degree-of-freedom (3-DOF) dynamic rig in the wind tunnel is modeled as a nonlinear affine system subject to mismatched disturbances. First of all, a baseline NDI attitude controller is designed for sufficient stability and good reference tracking performance of the nominal system. Then, a nonlinear disturbance observer (NDO) is supplemented to the baseline NDI controller to estimate the lumped disturbances for compensation, including unmodeled dynamics, parameter uncertainties, and external disturbances. Mathematical analysis demonstrates the convergence of the employed NDO and the resulting closed-loop system. Furthermore, an anti-windup modification is applied to the NDO for control performance preserving in the presence of actuator saturation. Subsequently, the designed control schemes are preliminarily validated and compared via simulations. The baseline NDI controller demonstrates satisfactory attitude tracking performance in the case of nominal simulation; the NDO augmented NDI controller presents significantly improved ability of disturbance rejection when compared with the baseline NDI controller in the case of robust simulation; the anti-windup modified scheme, rather than the baseline NDI controller nor the NDO augmented NDI controller, can preserve the closed-loop performance in the case of actuator saturation. Finally, the baseline NDI scheme and the NDO augmented NDI scheme are implemented and further validated in the wind tunnel flight tests, which demonstrate that the experimental results are in good agreement with that of the simulations.

Optimal fast charging is an important factor in battery management systems (BMS). Traditional charging strategies for lithium-ion batteries, such as the constant current–constant voltage (CC–CV) pattern, do not take capacity aging mechanisms into account, which are not only disadvantageous in the life-time usage of the batteries, but also unsafe. In this paper, we employ the dynamic optimization (DP) method to achieve the optimal charging current curve for a lithium-ion battery by introducing limits on the intercalation-induced stresses and the solid–liquid interface film growth based on an electrochemical–thermal model. Furthermore, the backstepping technique is utilized to control the temperature to avoid overheating. This paper concentrates on solving the issue of minimizing charging time in a given target State of Charge (SoC), while limiting the capacity loss caused by intercalation-induced stresses and film formation. The results indicate that the proposed optimal charging method in this paper offers a good compromise between the charging time and battery aging.

BACKGROUND:With rapid urbanization in the past decades, diet diversity continues to increase in China. The present cross-sectional study aims to explore the association between dietary diversity and nutritional status among adults in southwest China. METHODS:This study used data from 2011-2012 National Nutritional Survey in Yunnan Province, southwest China (N = 1105).Data of three consecutive 24-hour dietary recalls were used to calculate dietary diversity scores (DDS) and nutrient adequacy ratio (NAR). Body mass index and waist circumference were used to determine nutritional status. Surveylogistic procedure of SAS 9.2 software was used to examine the association between DDS and obesity by estimating odds ratio (OR) and 95% confidence intervals (CI). RESULTS:The mean DDS was 5.2 (SD 1.1) out of nine points. Being female, younger age, belonging to Han ethnicity, having higher educational level and household income were positively associated with DDS (all P