Direct and Indirect Effects of Parenting Style with Child Temperament, Parent-Child Relationship, and Family Functioning on Child Social Competence in the Chinese Culture: Testing the Latent Models

Interactional and contextual models have been conceptually proposed in understanding parental influences on children. Yet, empirical model testing has been limited. The purpose of this exploratory study was to investigate the direct and indirect effects of parenting style on child social competence using structural equation modeling in a sample of 544 Chinese families with 6-9 years old children, mainly singleton, residing in Nanjing, China. Five latent models were tested: (a) the direct model between parenting style and child social competence, (b) child temperament as a moderator, (c) parent-child relationship as a mediator, (d) the interaction model between parenting style and family functioning, and (e) bidirectional models of parenting style concurrently with parent-child relationship, and family functioning predicting child social competence. Findings showed: (a) The direct relationship between parenting style and child social competence was significant in both parents with authoritative parenting style on the positive direction, whereas authoritarian and permissive parenting styles on the negative direction; (b) child temperament did not moderate parenting style on child social competence; (c) father-child relationship mediated paternal parenting style on child social competence, whereas maternal parenting style did not; (d) family functioning neither moderated nor mediated the relationship between parenting style and child social competence for both parents; and (e) The four-factor prediction models on child social competence turned out to be unidirectional. For the mothers, the best model was from family functioning to mother-child relationship, to maternal parenting style, and finally to child social competence. Maternal parenting style was the significant proximal factor. For the fathers, it was from family functioning to paternal parenting style, to father-child relationship, and then to child social competence. Father-child relationship had the direct impact, whereas the influence of paternal parenting style was distal through father-child relationship. Findings from this study suggest that the Chinese parents should use more authoritative and less authoritarian and permissive parenting, and develop good parent-child relationships in the daily interactions with their children. Future studies need to use larger and better data to validate these models, or to extend the findings with other important child variables to explore the child's active agency

Development and Experimental Evaluation of an Automated Charge Testing Methodology for Domestic Refrigerators

Optimizing the refrigerant charge in a vapor compression cycle can lead to improvements in system performance and energy savings. Manufacturers often perform extensive experimental charge testing under different operating conditions to determine the optimal system charge of a certain product. However, the current de-facto industry standard procedure for performing such evaluation involves repeated charging and evacuating of equipment which is a time-consuming effort. In this work, an automated charge testing device and method were developed to perform a charge optimization for domestic refrigerators with the unit operating. This device consists of a combination of three solenoids to isolate a small calibrated volume of liquid refrigerant. This calibrated volume is typically around 2cc and allows a very small amount of refrigerant, usually less than 5 grams based on the density of liquid, to be charged into a unit with consistent accuracy and repeatability. This work also includes the development of a methodology for utilizing the device including software that automatically operates the device to charge the unit with additional refrigerant, collects and compares performance data, and detects when the optimal charge is reached to end the experiment. With the developed methodology, the entire procedure can be performed without human interaction saving a great amount of time and effort compared to conventional charge testing methods

Design of an electronically-actuated gas lift safety valve

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2013.Cataloged from PDF version of thesis.Gas lift valves are widely used in oil production fields to pump recycled gas and nitrogen into the production tubing, to sustain production by aerating the oil and lifting it to the ground or sea surface. Today's industry standard, a pressure-actuated valve, is susceptible to various modes of failure, including corrosion and jamming. Safety mechanisms are needed to seal the valve in case of a backflow event, in which oil flows backward through the production tubing. Since human monitoring is difficult to implement at deep level underground, these safety mechanisms have to be highly sensitive and autonomous. This thesis documents the design of an electronically-actuated gas lift safety system that builds on a prior invention based on shape-memory alloy, but, among other features, can handle the slowly changing temperature conditions downhole. The newly-designed control circuit is integrated into the original shape memory alloy (SMA) scheme. The selection criteria and features of various sensors in this circuit are reviewed in relation to oil's physical and chemical characteristics. System functionality is proved through model-scale prototype testing within a controlled environment. At the same time, the system is modeled with heat transfer and structural analysis to predict its behavior in different environments with air or water, or their mixture with oil. Overall, our concept satisfies many of the key operational needs in artificial gas lift.by Changkuan Yu.S.M

The effect of cyclic variation of shear stress on non-cohesive sediment stabilization by microbial biofilms : the role of ‘biofilm precursors’

This work was supported by the National Natural Science Foundation of China (NSFC, Grant Nos. 51620105005, 51879095, 51579072, 41606104). D. M. Paterson received funding from the MASTS pooling initiative (The Marine Alliance for Science and Technology for Scotland) and the NERC Blue-coast consortium (N E/N016009/1) and their support is gratefully acknowledged. MASTS is funded by the Scottish Funding Council (grant reference HR09011) and contributing institutions. X. D. Chen received funding from the China Scholarship Council.Biofilm mediated intertidal sediments exhibit more complex erosional behaviour than abiotic systems. A major feature of intertidal systems is the exposure to repeated cycles of high and low shear created by tidal conditions and also less predictable episodic events, such as storms. There is very little information on how biofilm-forming communities respond to these conditions. In this study, the effects of both single and repeated-cycles of shear on the stability of newly developed bio-sedimentary beds was examined. Cleaned sand, without any potential biostabilization, was used as the control. For the single-cycle scenario, biofilms were incubated on a non-cohesive sandy bed under prolonged low shear periods varying between 5 and 22 days, after which erosional stress was applied. No significant biostabilization was observed for the youngest bio-sedimentary bed (after five days of low shear incubation). After 22 days, microbial communities were characterized by a firmly attached surface biofilm. To cause erosion, greater hydrodynamic stress (0.28 Pa) was required. The erosional behaviour of the underlying sand was also affected in that bedform ripples noted in the control system were no longer observed. Instead, a sudden ‘mass erosion’ took place (0.33 Pa). The one-cycle scenario indicated that significant biostabilization of sand only occurred after a relative long calm period. Under repeated cycles of stress (five days of low stress followed by high stress event and re-incubation, repeated for four cycles = 20 days), frequent cyclic disturbance did not degrade the system stability but enhanced biostabilization. The properties of the sub-surface sediments were also affected where erosion rates were further inhibited. We hypothesize that organic material eroded from the bed acted as a ‘biofilm precursor’ supporting the development of new biofilm growth. A conceptual framework is presented to highlight the dynamics of bio-sedimentary beds and the effects of growth history under repeated-cycles.PostprintPeer reviewe

Biological cohesion as the architect of bed movement under wave action

Funding for this project was provided by the National Key Research and Development Project, MOST, China (2018YFC0407506), the National Natural Science Foundation of China (51620105005), and the China Postdoctoral Science Foundation (2020M680580). D. M. Paterson acknowledges NERC funding (NE/N016009/1).Cohesive extracellular polymeric substances (EPS) generated by microorganisms abundant on Earth are regarded as bed “stabilizers” increasing the erosion threshold in sedimentary systems. However, most observations of this phenomenon have been taken under steady flow conditions. In contrast, we present how EPS affect the bed movement under wave action, showing a destabilization of the system. We demonstrate a complex behavior of the bio‐sedimentary deposits, which encompasses liquefaction, mass motion, varying bed formations and erosion, depending on the amount of EPS present. Small quantities of EPS induce higher mobility of the sediments, liquefying an otherwise stable bed. Bed with larger quantities of EPS undergoes a synchronized mechanical oscillation. Our analysis clarifies how biological cohesion can potentially put coastal wetlands at risk by increasing their vulnerability to waves. These findings lead to a revised understanding of the different roles played by microbial life, and their importance as mediators of seabed mobility.Publisher PDFPeer reviewe

Study on the improvement of the open TBM system and supporting equipment based on the Gaojiapu Coal Mine

In order to cope with multi-dimensional mine disasters in deep mines, enhance the adaptability of the open tunnel-boring machine (TBM) to the actual mine working face environment, and improve the excavation speed of the open TBM, based on the excavation project of Gaojiapu Coal Mine in Zhengtong Coal Industry, Shaanxi Province, this paper comprehensively considers the difficulties encountered by the TBM in the excavation process and improves the open TBM system and its supporting equipment. The research shows that removing the redundant system and supporting equipment of the open TBM can effectively solve the difficulties of the TBM entering the mine, such as loading and unloading, and turning; optimizing the open TBM shield, shortening the main beam, and setting the support platform and jumbolter system on the main beam can deal with the problem that the TBM support is not timely and easy to jam. Opening circular holes and installing slag cleaning guide plates on the main beam of the open TBM can timely clean up the waste slag on the main beam and protect the main beam from deformation. Installing a slag cleaning bucket wheel machine between the main beam of the open TBM and the trailer can reduce the accumulation of waste slag on the road ahead. Compared with ordinary excavation construction technology, the monthly average footage level of the open TBM after technical improvement is 300.88 m, which is 3.8 times that of the rock roadway general excavation and 1.6 times that of the rock roadway comprehensive excavation