The phase stability and thermophysical properties of InFeO3(ZnO)m (m = 2, 3, 4, 5)

The phase stability and thermophysical properties of InFeO₃(ZnO)_m (m = 2, 3, 4, 5) compounds were investigated, which are a general family of homologous layered compounds with general formula InFeO₃(ZnO)_m (m = 1–19). InFeO₃(ZnO)_m (m = 2, 3, 4, 5) ceramics were synthesized using cold pressing followed by solid-state sintering. They revealed an excellent thermal stability after annealing at 1450 °C for 48 h. No phase transformation occurred during heating to 1400 °C. InFeO₃(ZnO)₃ exhibited a thermal conductivity of 1.38 W m⁻¹ K⁻¹ at 1000 °C, which is about 30% lower than that of 8 wt.% yttria stabilized zirconia (8YSZ) thermal barrier coatings. The thermal expansion coefficients (TECs) of InFeO₃(ZnO)m bulk ceramics were in a range of (10.97 ± 0.33) × 10⁻⁶ K⁻¹ to (11.46 ± 0.35) × 10⁻⁶ K⁻¹ at 900 °C, which are comparable to those of 8YSZ ceramics.     

Allocation of assembly tolerances to minimize costs

The cost and quality of an assembly depend on the processes used to manufacture its components. The specific processes and process settings are often dictated by the tolerances on the components. One long-standing challenge is allocating the assembly tolerance to components. Many methods have been proposed, most of which endeavor to minimize cost. We propose a tolerance allocation method that minimizes cost by jointly considering process variation and tolerance specifications. A cost model including processing cost, scrap cost, and quality loss is employed. The cost is minimized by a heuristic strategy. An overrunning clutch assembly case study is used to evaluate the method.     

Comparison of graphene growth on arbitrary non-catalytic substrates using low-temperature PECVD

Conventional Chemical Vapor Deposition (CVD) techniques require the use of a catalyst surface and high temperature of growth (∼1000 °C) to grow graphene, which renders the process incompatible with arbitrary substrates. While post-synthesis transfer of graphene onto required substrates is widely used, it causes undesirable effects such as wrinkles/folds/cracks and unintentional doping. Here, we report low-temperature growth of graphene at 650 °C on non-catalytic SiO₂ and quartz substrates using a one-step, rapid Plasma Enhanced Chemical Vapor Deposition (PECVD) process. We simultaneously study PECVD graphene growth on a traditional catalytic material such as copper and show that the growth substrate does not play any role in the dissociation of hydrocarbon precursor during PECVD, thus eliminating the possibility of a catalytic effect. Using several characterization techniques, we observe an increasing rate of growth from SiO₂ to quartz to copper, which can be attributed to different adsorption and diffusion energies of plasma radicals on these substrates. As opposed to thermal CVD growth on copper, which is self-limiting, the PECVD method developed here is scalable in terms of number of layers, allowing its adept integration in commercial devices.     

Development and evaluation of virtual refrigerant mass flow sensors for fault detection and diagnostics

Refrigerant mass flow rate is an important measurement for monitoring equipment performance and enabling fault detection and diagnostics. This paper presents and evaluates three different virtual refrigerant mass flow (VRMF) sensors that use mathematical models to estimate flow rate using low cost measurements. The first model uses a compressor map that relates refrigerant flow rate to measurements of condensing and evaporating saturation temperature, and to compressor inlet temperature measurements. The second model uses an energy-balance method on the compressor that uses the compressor power consumption. The third model is developed using an empirical correlation for an electronic expansion valve (EEV) based on an orifice equation. The three VRMFs are shown to work well in estimating refrigerant mass flow rate for various systems under fault-free conditions with less than 5% RMS error. The combination of the three VRMFs can be utilized to detect and diagnose when the compressor and/or expansion device is not providing the expected flow.     

Effects of high hydrostatic pressure on lipase from Rhizopus chinensis: I. Conformational changes

Conformational changes of Rhizopus chinensis lipase (RCL) induced by high hydrostatic pressure processing, were evaluated by molecular dynamic (MD) simulations and experimental methods. In most lipases a lid covers the substrate binding site keeping the lipase active when the lid is open, whereas the lipase is inactive when the lid is close. Results of this research showed that lid was closed when high pressures in the range 400–600 MPa were applied, whereas it was open at pressures around 200 MPa, at which the lipase exhibited a high activity. Simulations and Circular dichroism (CD) tests confirmed that the lid length kept constant at all pressures. At pressures around 200 MPa, hydrogen bonds between the amino acids Ser145 and His257 was preserved whereas at pressures around 600 MPa, hydrogen bonds between the amino acids His257 and Asp204 was significantly weakened Docking studies suggested that the highest and lowest binding affinity between the enzyme active site and the substrate occurred when pressures of 200 and 600 MPa, were applied, respectively.The enzyme tertiary structure changed significantly at pressures higher than 500 MPa. The presence of the amino-acid Lys202 near the active site plays a key role in determining the fluorescence properties and fluorescence spectra of RCL. MD simulations confirmed that was the reason for changes in fluorescence observed at pressures over 200 MPa.     

Research on outlier detection algorithm for express logistics

To detect the problems of time delay, path error and destination error in express logistics process effectively, a novel outlier detection algorithm for express logistics is proposed in this paper. To test the detection results, the express logistics system operating model is built to test the detection results. Experiment results show that the proposed algorithm is well applied to the express logistics data with multi-attribute characteristics, and can work well in detecting the abnormal conditions of express logistics.     

Dynamic centrifuge tests on isolation mechanism of tunnels subjected to seismic shaking

Isolation layer is one of the countermeasures to enhance seismic safety of tunnels. Its behavior under earthquake is affected by many factors such as shape of the tunnel, stiffness of the isolation layer and the characteristics of the input motion. However, current knowledge on the effects of these parameters on the seismic behavior of isolation layer is limited to lack of experimental data. This paper focuses on the mechanism of isolation layer, especially the efficacy of input motion frequencies on the seismic behavior of a square tunnel with isolation layer around its outer surface. Dynamic centrifuge tests were carried out on model tunnels which took isolation layer as seismic countermeasure using input motion of sinusoidal waves of different frequencies. Actual records of ground motions, magnified to approximate 15 g peak acceleration, formed the basis of the excitations to verify the actual efficacy. Due to the difference between model material (aluminum alloy) and prototype material (concrete), the similar flexural deformation law and the similar axial deformation law could not be satisfied simultaneously. Given the fact that cross-sectional moments were one of the main factors that influenced the safety of tunnels under dynamic loadings, the similar flexural deformation law was accepted in model preparation. The results show that the bending strains of tunnel with isolation layer around its outer surface are lower than those of tunnel without isolation layer, which indicates that isolation layer has positive effect on moment reduction, especially at corners. Increasing of the input motion frequency decreases the dynamic cross-sectional bending moments. In addition, isolation layer has little influence on frequency contents of acceleration response of tunnel. This study has clarified the mechanism of isolation layer on shock absorption, which is proved to be an effective method to improve the safety of tunnel against earthquake.     

The influence of curing on restrained shrinkage cracking of bonded concrete overlays

The influence of seven practical curing regimes on restrained shrinkage cracking of bonded concrete overlays was investigated. The influence of the curing regimes on the individual material properties governing restrained shrinkage cracking and on the age at cracking and crack area of ring tests and composite overlay–substrate specimens was investigated for three laboratory-made mixes of differing strengths and one commercial repair mortar. The results of the experimental testing showed that curing influences all of the material properties governing restrained shrinkage cracking. Prolonged or more effective curing was shown to either delay or reduce the rate of shrinkage respectively (dependent on the curing method), increase the tensile strength and elastic modulus, and decrease the tensile relaxation. In general, prolonged or more effective curing was shown to have a positive influence on restrained shrinkage cracking by increasing the age and net age at cracking.     

Network Design Model to Integrate Shelter Assignment with Contraflow Operations in Emergency Evacuation Planning

Networks and Spatial Economics - In traditional emergency evacuation planning, shelter assignment and contraflow operations are determined sequentially. In this paper, we show that these two types...     

Performance limit for economized cycles with continuous refrigerant injection

While economizing can improve the performance of vapor compression cycles, the cost of multi-stage compressors has limited its implementation to large-scale applications. However, the development of compressors with injection ports presents new opportunities for economizing in smaller-scale applications. In addition to eliminating the need for a costly multi-stage compressor, multiple injection ports can be added at relatively low cost to further improve cycle performance. In the current study, a model was developed to study the effect of the number of injection ports on performance and determine the limit to performance with injection. The model predicts that continuous injection, in which economized refrigerant is injected at an infinite number of ports to maintain saturated vapor in the compressor, provides very significant performance improvements for air-conditioning and refrigeration applications. At standard operating conditions, the COP increases between 18% and 51% depending on the application, with higher temperature lift cycles benefiting most significantly.