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Shell-and-tube heat exchangers are widely used in many research fields and industrial production processes, but little research has been conducted on the use of heat exchangers for drying crops. This study conducted a numerical simulation of the temperature, velocity, and pressure fields based on the shell-and-tube fluids of a heat exchanger in a biomass particle hot-blast stove. The correctness of the simulation results was verified by test data before simulation, and the mesh was verified to be irrelevant. The application of a multi-objective genetic algorithm in heat exchanger design and optimization was explored, considering five design variables, such as hot tube diameter, transverse pitch, longitudinal pitch, cold flow velocity, and hot flow velocity for optimization. The Nusselt number, friction factor, and comprehensive performance coefficient were used as objective functions for 2D and 3D response surface analysis. The final design variables P1=74.91 mm, P2=104.23 mm, P3=121.37 mm, P4=4.83 m/s, and P5=8.48 m/s were obtained to improve the comprehensive performance coefficient by 16.11%. The heat transfer performance was improved by 9.55% and the resistance performance was reduced by 15%.

In view of the low control precision, low degree of intelligence, low utilization rate of soybean milk, and poor conjunctiva quality in current Yuba skin production technology, a system of multifactor control and intelligent quality detection for Yuba skin was studied and designed in this paper. The system uses LabVIEW as the upper computer and the single chip microcomputer as the lower computer. Uses programming electronic control technology to set process parameters in advance, precisely control each factor to achieve adaptive control of wind speed, concentration, liquid level, and temperature, the control error of each factor is within 1%, and the quality of Yuba skin was detected by image processing technology. The application of the system greatly improves the production efficiency and intellectualization of the production line and reduces the damage degree of Yuba skin. An orthogonal test and response surface optimization were carried out for the process parameters. The test results show that the accuracy of the test results using radial basis kernel function (RBF) can reach 92.06% when the characteristic combination mode is all the characteristics, and the optimal yield will be 48.57% and the optimal quality score is 9.20 when the export angle is 36.75°, the export diameter is 9.90 mm, the export wind speed is 1.22 m/s, the slurry concentration is 7.66%, the slurry temperature is 83.26°C, and the liquid level is 30.52 mm. Comparison between the results from the regression model validation test and those from the response surface methodology is made. The relative errors of yield and quality were 0.14% and 0.87%, which indicates that the response surface methodology can effectively optimize the process parameters of Yuba skin.

At present, the surface quality of Yuba skin is determined by sensory methods. In order to realize the intelligent classification detection of Yuba skin quality, this study designed a system that automatically determines the quality of Yuba skin surfaces based on image processing and support vector machine (SVM) approaches. Specifically, the system uses image preprocessing to extract the grayscale eigenvalues, gray level co-occurrence matrix (GLCM) eigenvalues, and gray level run length matrix (GLRLM) eigenvalues of the sample image and uses them as input values for a quality grading system. Through model evaluation of three classification models, the SVM classification model was selected according to the evaluation results, and different kernel functions were used in the model for sample training. Based on Matlab, the quality grading software of Yuba skin was developed and designed. Intelligent detection and grading were realized through the radial basis kernel function support vector machine (RBF-SVM) grading model. The best penalty factor (c = 3.50) and kernel parameter value (g = 0.98) were obtained through cross-validation. The accuracy of the model was 95.31% and 94.16% for the training and test sets, respectively. The grading accuracy of the RBF-SVM grading system was 93.56%, and the error was less than 5% compared with the traditional sensory method of grading; thus, the quality classification method based on the SVM classification system for Yuba skin is feasible and can be used for quality detection.

Few studies have explored the influences of children’s justice. The present study investigated the associations of parents’ and peers’ justice with children’s justice based on the perspectives of intergenerational similarity and peer homophily. A total of 761 fourth- to ninth-graders aged 10–15 years old (Mean age = 12.62, SD = 1.74; 45.2% boys) and their mothers, fathers, and reciprocal playmates participated in this study. The justice subscale of the Values in Action Inventory of Strengths for Adults (VIA-IS) and Youth (VIA-Youth) was used to measure the justice of each party. A multilevel regression analysis showed that high levels of mothers’, fathers’, and playmates’ justice were associated with a high level of children’s justice. Two-way interactions were found between mothers’ and playmates’ justice. Simple slope analyses showed that mothers’ high level of justice was related to high justice in children when playmates’ justice was low. Similarly, playmates’ high level of justice was related to a high level of justice in children when mothers’ justice was low. Moreover, multigroup analysis indicated gender differences in that the interaction and its compensatory effect were only observed in boys but not in girls. The findings also suggest a positive linkage of parents’ and peers’ justice with children’s justice and a compensatory interaction mechanism between mother and peer systems, which enriches evidence in the relevant research field and contributes to our knowledge of children’s virtue development.

The tilting of the tractors' seat during deep tillage operations affects the drivers' sitting position, which can lead to lumbar spine injuries. To investigate the effect of seat tilting on the driver's L4 biomechanics, we built a tractor-driver musculoskeletal model in AnyBody™. The maximum activity of the driver's erector spinae at different tilted angles were measured by sEMG and compared with the simulation results to validate the model. The spatial position of the driver's spine at different tilted angles were obtained by 3 D motion capture. The model simulated the driver's spine posture during the actual tilt and investigated the effects of different tilted angles and vibration on the biomechanics of the driver's L4 . The results showed that as the tilt angle of the tractor increased, the load on the driver's L4 also increased, especially the shear force increased at a faster rate than the axial and normal forces, with the shear force on the driver's L4 increasing from 0 N to 138.7 N when the tractor was tilted from 0° to 15°. When vibration was applied to the musculoskeletal model, the maximum value of the shear force on the driver became progressively greater as the angle of tilt of the tractor increased. Overall, tilting the tractor can have a large impact on the biomechanics of the driver's L4, and tilting the tractor may be an important cause of lumbar spine injuries for tractor drivers.

Multi-user millimeter wave (mmWave) massive multi-input multi-output (MIMO) is a promising technology for the next generation mobile communication systems. However, there are still unsolved problems before such commercial MIMO networks are rolled out. One main issue is the hardware cost and power consumption which grow significantly as the number of radio frequency (RF) components increases. To tackle this issue, we consider to deploy one-bit analog-to-digital converters (ADCs) and digital-to-analog converters (DACs) at the base station (BS), and study uplink (UL)/downlink (DL) channel estimation and DL precoding techniques for the associated MIMO systems with one-bit ADCs/DACs. Specifically, we first formulate the UL channel estimation as an one-bit compressed sensing problem, and then devise an efficient gridless generalized approximate message passing-based (GL-GAMP) algorithm to handle it. Additionally, we develop an exhaustive search based proximal gradient descent method (PGM) for DL channel estimation. Note that with slight modifications, we show that PGM can also be applied to solve the DL precoding problem. Simulation results showcase that our methods have advantages over the state-of-the-art techniques and are able to offer good trade-offs between accuracy and computational complexity, which ultimately indicates their superiority in the application of mmWave MIMO systems with one-bit ADCs/DACs.

As tractors mainly transit rural roads, drivers can suffer from harmful vibrations transmitted though their seats. Thus, the driving comfort in tractors with agricultural equipment should be evaluated. To investigate the effects of forward motion and front-wheel steering on the driving comfort of two-wheel-drive tractors with agricultural equipment, we establish a man–machine–road virtual prototype for simulations and validate it experimentally. First, a tractor that has suspended agricultural equipment and is operating at front-wheel steering angles of 0°, 12°, 24°, and 36° is driven on a random level-D road. Simultaneously, the vibration accelerations experienced by the driver are obtained along the X, Y, and Z axes with the coordinate system defined according to the ISO 2631-1 standard. The combined weighted root-mean-square (RMS) acceleration corresponding to the driver’s whole-body vibration increases from 0.205 to 0.909 m/s2 when increasing the steering angle. Then, considering the forward speed as the variable, the front-wheel steering angle is set at 30°, and the vibration accelerations experienced by the driver are obtained when the tractor travels at 4, 5, and 6 km/h on a random level-D road. The combined weighted RMS acceleration corresponding to the driver’s whole-body vibration increases from 0.68 to 1.03 m/s2 when increasing the speed. Therefore, we found that the velocity of a tractor should be reduced while steering, and excessively large front-wheel steering angles should be avoided to increase driving comfort.

Highlights The drying effect in the drying layer is affected by the status of the flow field. The angular box of the drying oven is optimized to improve the drying effect. The structure of the variable-section angular box significantly reduced unevenness and improved the drying effect. Abstract . Dryers are subject to problems as they are unable to fully and uniformly dry grain. Considering the mixed-flow drying process and improving the drying uniformity, this study conducted a numerical simulation of the hot air temperature field, velocity field, and pressure field with ordinary equal cross-section. The dryer was optimized by a variable-section angular box structure for simulation analysis and experimental verification. The results demonstrated the following: the optimized variable cross-section angular box can improve the uniformity of the overall flow of hot air in the drying box; that is, it diffuses uniformly in the temperature, speed, and pressure field of hot air. A comparative analysis of equal cross-section and variable cross-section angled tubes indicated that the unevenness coefficient of the tubes’ wind field of the same section was reduced from 81.31% to 66.8%, 51.19% to 32.78%, and 56.98% to 42.57%, which significantly reduced unevenness and improved the drying effect. Keywords: Angular box, Flow field distribution uniformity, Grain drying, Numerical simulation.

Millimeter wave (mmWave) multi-user massive multi-input multi-output (MIMO) is a promising technique for the next generation communication systems. However, the hardware cost and power consumption grow significantly as the number of radio frequency (RF) components increases, which hampers the deployment of practical massive MIMO systems. To address this issue and further facilitate the commercialization of massive MIMO, mixed analog-to-digital converters (ADCs) architecture has been considered, where parts of conventionally assumed full-resolution ADCs are replaced by one-bit ADCs. In this paper, we first propose a deep learning-based (DL) joint pilot design and channel estimation method for mixed-ADCs mmWave massive MIMO. Specifically, we devise a pilot design neural network whose weights directly represent the optimized pilots, and develop a Runge-Kutta model-driven densely connected network as the channel estimator. Instead of randomly assigning the mixed-ADCs, we then design a novel antenna selection network for mixed-ADCs allocation to further improve the channel estimation accuracy. Moreover, we adopt an autoencoder-inspired end-to-end architecture to jointly optimize the pilot design, channel estimation and mixed-ADCs allocation networks. Simulation results show that the proposed DL-based methods have advantages over the traditional channel estimators as well as the state-of-the-art networks., Comment: 13 pages, 12 figures. Submitted to IEEE Transactions on Wireless Communications

The noise comfort of a tractor is a key factor in the evaluation of tractor comfort, and it has a significant impact on the evaluation of the overall performance evaluation of a tractor. This paper used the rating scale method to evaluate the sound quality of each operation state and position of the tractor, and obtain the evaluation value of the tractor noise. In addition, objective parameters of the sound (including the sound pressure level, A-weighted sound pressure level, loudness, sharpness, roughness, and fluctuation strength) were calculated. By considering objective parameters of sound quality as input and sound quality evaluation values as output, we established back propagation neural network (BPNN) model and support vector regression (SVR) model. Furthermore, the initial weights and thresholds of the BPNN model, penalty parameters, insensitive loss parameters, and kernel function parameters of the SVR model were optimized by genetic algorithm (GA). After verification of the experimental results, it was observed that the GA could improve the prediction accuracy of the model and significantly reduce the extreme errors. Compared with the prediction results of other prediction models, the GA–SVR model predicted the sound quality value of tractor noise with higher accuracy and stability.

Asymmetries in social status, specifically social status related to wealth and relational power, appear to influence the ways in which children allocate resources. However, the impact of wealth and relational power status on children’s resource allocation decisions has yet to be examined among children developing within a Chinese cultural context. In addition, how children weight the relative importance of these factors when they exist concurrently is not well understood. In Study 1, we examined the impact of recipients’ wealth and relational power status on Chinese children’s (3- to 8-year-olds; N = 199) allocation decisions. We found that across both categories of social status, 3- and 4-year-olds gave more to high-status individuals, whereas 7- and 8-year-olds gave more to low-status individuals, despite younger children also showing a strong egalitarian preference when the resources could be allocated equally. In Study 2, we investigated how children (3- to 8-year-olds; N = 219) weigh the relative importance of these two types of social status in situations where the level of recipients’ wealth and relational power were either consistent or in conflict. When they needed to allocate the resources unequally, the youngest children were found to place greater emphasis on wealth over relational power and favored the high-status individual, whereas older children tended to favor the low-status individual and placed greater importance on relational power over wealth. Overall, we found a consistent age-related shift from favoring high-status individuals toward compensating low-status individuals, suggesting a developing concern for social equity.

Introduction Peers are an important source of influence on children's social development. This study investigated the positive association between peers' and children's interpersonal character (i.e., humanity and justice) and the moderating role of children's and peers' social status including wealth (family SES), power (class leadership), and prestige (social preference and social visibility). Methods The participants were 1555 fourth-to ninth-graders (Mage = 12.76; 46.9% boys) and their reciprocal playmates in China. Questionnaires and peer nomination methods were used to measure interpersonal character and social status. Children's reciprocal playmates were used as the source of peer influence. Results The playmates' humanity and justice were positively associated with the children's humanity and justice regardless of the child's grade, gender, or sibling status. Children's level of social visibility moderated the associations between the playmates' and the children's humanity and justice, with children of low social visibility being more strongly influenced by their playmates. The moderating role of playmates' social status was displayed in two modes and appeared in the secondary school and singleton samples. First, playmates with a higher social preference were more closely related to secondary school children's justice; second, playmates with lower social visibility were more closely related to secondary school children's and singletons' justice. Conclusions The findings confirm the positive relationships between peers' and children's interpersonal character and reveal an important moderating role of prestige status, especially social visibility, among the relationships. This study extends the research on positive peer influence and contributes to knowledge of peer influence mechanisms.

This paper considers channel estimation and uplink achievable rate of the coarsely quantized massive multiple-input multiple-output (MIMO) system with radio frequency (RF) impairments. We utilize additive quantization noise model (AQNM) and extended error vector magnitude (EEVM) model to analyze the impacts of low-resolution analog-to-digital converters (ADCs) and RF impairments respectively. We show that hardware impairments cause a nonzero floor on the channel estimation error, which contraries to the conventional case with ideal hardware. The maximal-ratio combining (MRC) technique is then used at the receiver, and an approximate tractable expression for the uplink achievable rate is derived. The simulation results illustrate the appreciable compensations between ADCs' resolution and RF impairments. The proposed studies support the feasibility of equipping economical coarse ADCs and economical imperfect RF components in practical massive MIMO systems., 6 pages, 4 figures. Submitted to IEEE Communications Letters. Already accepted for publication by IEEE but not published yet

Research on primary and secondary school composition has shown that a school's socioeconomic status, as an aggregated and stratified index, has a contextual effect on children's school performance. For Chinese children, preschool is their first formal schooling experience. Preschools are segregated by the enrolled children's socioeconomic status. However, no studies have yet examined the role of preschool socioeconomic status in young Chinese children. Taking family socioeconomic status as the structure index and the home learning environment and authoritative parenting as the process indexes, the current study aimed to examine how preschool socioeconomic status operates independently and moderates the family environment to determine Chinese children's early academic and social development. Data were obtained from 826 children aged 36–74 months from 29 urban preschools in Beijing. Hierarchical linear modeling analyses showed that preschool socioeconomic status significantly directly predicted children's academic skills but not their social skills. Participation in higher socioeconomic status preschools appeared to compensate for the literacy skills of children from a lower family socioeconomic status, and it reinforced the positive effects of authoritative parenting on the children's social skills. These results suggest that the optimal development of young children depends on the “fit” between their family's environmental characteristics and the preschool in which they enrolled.

A multilevel modeling approach was employed to investigate the relationship between preschool rural migrant composition and the pre-academic and behavioral outcomes of young rural migrant children with different durations of residence in urban China. This study represents a unique contribution because (1) few studies have focused on young Chinese rural migrant children and examined the influence of preschool rural migrant composition on their academic skills and behaviors, (2) few researchers in China have used a continuous (i.e., percentage of rural migrants in school) as opposed to a binary (i.e., mixed school versus rural migrant school) indicator for school rural migrant composition, and (3) few investigations have distinguished groups of rural migrant children by the duration of urban residence (i.e., short-duration (SD) rural migrant children versus long-duration (LD) rural migrant children). Based on data of 1213 Chinese children (2.7–6.17 years of age) and their parents and teachers from 81 urban preschools in Beijing, we found that SD rural migrants (≦2.5 years) were rated significantly lower in oral language and numeracy skills and that LD rural migrants (>2.5 years) were rated as having significantly more behavioral problems than their urban counterparts after controlling for the children’s gender, age, family socioeconomic status (SES) and preschool SES. Cross-level interactions indicated that SD rural migrant children in preschools with proportionally more rural migrant peers fared better in terms of oral language skills, and LD rural migrant children had fewer behavioral problems when there were more rural migrant peers in their preschools, whereas urban children performed worse in terms of oral language skills and displayed more behavioral problems in preschools with a high rural migrant composition. These findings provide insights into improving the early development and adaptations of rural migrant children.

The parent-peer relationship spillover theory holds that individuals are embedded in various interdependent social systems (e.g., parent-peer systems) and there is a spillover between parent–child and peer relationships. This study applied this theory to explore a direct and indirect (through children’s interpersonal character and academic achievement) linkages between parent–child relationships (i.e., parental time with children, parent–child closeness and conflict) and children’s peer relationships (i.e., peer acceptance and rejection) in China. Participants were 992 fourth- to ninth-graders (48.1% male; Mage = 12.6 years) and both their parents. Multiple sources of information (parent reports, self-ratings, sociometric methods, and achievement data) was used. The results showed that: (1) For the direct linkage, mother–child conflict was positively linked to children’s peer rejection, father–child conflict was negatively linked to children’s peer acceptance. (2) For the indirect linkage, children’s interpersonal character and academic achievement played distinct driving mechanisms linking parent–child relationships to peer relationships. Specifically, the higher levels of mother–child and father-child closeness were related to better interpersonal character of children which, in turn, is associated with peer acceptance. By contrast, the higher levels of mother–child and father-child conflict were linked to children’s lower acceptance and higher rejection from peer through lower levels of academic achievement. These findings support the spillover theory and provide relevant empirical evidence from China, and advance our understanding of parental functioning on children’s peer relationships within Chinese culture.

From early in life, children show sensitivity to both merit and group membership. However, little research has examined how children react to the conflicting demands of allocating meritoriously and favoring in-groups during resource allocation over the course of their development. We compared how children aged 3–5 years and children aged 6–8 years allocated and reasoned about allocations to in-group and out-group members in a merit-based context. In Study 1, in four distribution tasks, children needed to allocate resources to high- and low-merit persons who were either in-group or out-group members and then indicate the reasons for their decisions. In Study 2, we chose the condition where the conflict between merit and group bias was strongest and further tested the effect of merit and group bias. We found that children prioritized merit across conditions, whereas in a context where the conflict was sufficiently intense they also took group membership into consideration. In addition, with age, children incorporated the conflicting demands of merit and group bias during resource allocation. The findings suggest that, with age, children weighed the moral concerns of merit and the social concerns of group bias when determining the allocation of resources.

Interpersonal strengths are important positive traits of human beings. This study investigated the phenomenon and mechanisms of the intergenerational transmission of interpersonal strengths. A total of 992 fourth-to ninth-grade children (48.1% boys, Mage = 12.63) and both mothers and fathers in China were involved in the present study. The results showed that fathers' (but not mothers') interpersonal strengths were directly associated with children's interpersonal strengths. Different transmission mechanisms of mothers and fathers were found: mother-child relationships and fathers' parenting styles explained the association between parents' and children's interpersonal strengths and between marital relationships and children's interpersonal strengths. Consistent transmission effects and mechanisms were found across child grade, gender, and sibling status. The findings of the current study provide evidence of intergenerational correlations for both parents regarding interpersonal strengths. Parents (especially fathers) with interpersonal strengths can raise children with corresponding strengths through particular family processes regardless of child characteristics.

article i nfo Investigations regarding the differences between Chinese only and non-only children primarily examine children's social behaviors, which are closely related to their early relationships with mothers and teachers. In recent years, the number of non-only children born in urban areas has increased because of the softening of the One-Child Policy, which leads to the distribution of non-only children shifting from being primarily in rural areas to being in both urban and rural areas. The present study investigates the current characteristics and influ- ences of mother-child and teacher-child relationships on Chinese only and non-only children's early social behaviors from the perspective of urban and rural differences. Data were obtained from 126 rural only children, 94 rural non-only children, 168 urban only children and 155 urban non-only children from 38 semi-urban kindergartens in Beijing, China. Hierarchical multiple regression analyses found that mother-child closeness positively predicted children's social skills particularly in non-only children, whereas mother-child conflict pos- itively predicted internalizing behavior problems in all four groups. Teacher-child conflict negatively predicted children's social skills most strongly in urban only children. Teacher-child conflict aggravated rural only children's, urban only children's and non-only children's internalizing and externalizing behavior problems, but mother-child closeness buffered rural only children's externalizing behavior problems. Findings underscore the importance for mothers to improve closeness, especially with rural only children, and for teachers to avoid conflict with both urban only and non-only children, as well as with rural only children. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license

To observe the effect of rectus femoris island myocutaneous flap for repairing bedsores in III and IV phases at the femoral greater trochanter area as a result of paraplegia.Thirteen paraplegic patients who suffered bedsores in III and IV phases at the greater trochanter of femur area were hospitalized from July 2009 to June 2013. The bedsores ranged from 4.5 cm×4.0 cm to 10.0 cm× 9.0 cm in area. After debridement, the size of soft tissue defect ranged from 5.0 cm×4.5 cm to 10.5 cm×10.0 cm. Rectus femoris island myocutaneous flaps were used to repair these defects, with flap area ranging from 5.0 cm×5.0 cm to 11.0 cm×10.0 cm and muscular pedicle length ranging from 8 to 12 cm. The donor sites of muscular pedicle were closed by direct suture, while those resulted from forming myocutaneous flap were closed by the transplantation of autologous skin obtained from thigh.Necrosis appeared at the edge of myocutaneous flap in one patient, and it was healed after dressing change. The other 12 myocutaneous flaps survived well. Patients were followed up for 2 to 30 months, and bedsore did not recur.Rectus femoris island myocutaneous flap, with characteristics of reasonable design, large donor area, big rotation angle, and with wear-, tear-, and pressure-resistance, is suitable for repairing bedsores at III and IV phases at the greater trochanter of femur area in paraplegic patients.