Design and Simulation of Small Space Parallel Parking Fuzzy Controller

Based on the nonlinearity and time-variation of automatic parking path tracking control system, we use fuzzy control theories and methods to explore the control rules to improve fuzzy controllers and design an automobile steering controller. Then we build the simulation experiment platform of an automobile in Simulink to simulate the reversing settings of parallel parking. This paper adopts the Mamdani control rules; the membership function is the Gauss function. This paper verifies the fuzzy controller's kinematic model and the advantages of fuzzy control rules. Simulation results show that the design of the controller allows the automobile to stop into the parking space smaller than the space obtained by planning path, and automatic parking becomes possible in the parking plot. The control system is characterized by small tracking error, fast response and high reliability

Expression and non-chromatographic purification of 1,3-propanediol oxidoreductase in Escherichia coli

The gene dhaT from Klebsiella pneumoniae encodes 1,3-propanediol oxidoreductase (PDOR). Thermally responsive elastin-like polypeptides (ELPs) was used as a fusion tag to purify the proteins (PDOR). The ELP gene was attached to dhaT and ligated into the pET-22b vector. Different NaCl concentrations were employed to decrease the transition temperature (Tt) which was diminished as salt concentration increased. The optimal final concentration of NaCl was 1 M and the corresponding Tt was 39.5\ubaC. Enzymatic assays were determined via every step for purification of fusion PDOR. PDOR showed good stability during the purification process, the specific activity in the first and second round of inverse transition cycling (ITC) was 276.1 \ub1 13.3 and 213.3 \ub1 10.8 U/mg, respectively. The ELPs fusion PDOR was superior to histidine tagged PDOR in both yield and activity after the purification

Codon optimization of 1,3-propanediol oxidoreductase expression in Escherichia coli and enzymatic properties

The gene dhaT from Klebsiella pneumoniae encoding 1,3-propanediol oxidoreductase (PDOR) was de novo synthesized by splicing overlap extension polymerase chain reaction (SOE-PCR) primarily according to Escherichia coli's codon usage, as well as mRNA secondary structure. After optimization, Codon Adaptation Index (CAI) value was improved from 0.75 to 0.83, meanwhile energy of mRNA secondary structure was increased from -400.1 to -86.8 kcal/mol. This synthetic DNA was under control by phage T7 promoter in the expression vector pET-15b and transformed into the E. coli BL21 (DE3) strain. Inducers such as isopropyl \u3b2-D-thiogalactoside (IPTG) and lactose were compared by activity at different inducing time. The activity of PDOR after codon optimized was 385.4 \ub1 3.6 U/mL, which was almost 5-fold higher than wild type (82.3 \ub1 1.5 U/ml) under the flask culture at 25\ub0C for 10 hrs. Then his-tagged enzyme was separated by using Ni-IDA column. The favorite environment for enzyme activity was at 5\ub0C and pH 10.0, PDOR showed a certainly stability in potassium carbonate buffer for 2 hrs at diverse temperatures, enzyme activity was significantly improved by Mn2+

Shaking table tests on gravel slopes reinforced by concrete canvas

The behaviour and performance of different reinforced slopes during earthquake loading were investigated through a series of shaking table tests. Concrete-canvas and composite reinforcement (geogrid attached to concrete-canvas) were proposed for reinforcing slopes. By considering the effects of different reinforcement methods, the seismic responses of the reinforced slopes were analysed, along with the accelerations, crest settlements, and lateral displacements. The failure patterns of different model slopes were compared using white coral sand marks placed at designated elevations to monitor the internal slide of the reinforced slopes. Both the concrete-canvas and composite reinforcement could increase the safety distance, which ranged from the slide-out point to the back of the model box. The composite reinforcement decreased the volume of the landslide and increased the failure surface angle as a result of the larger global stiffness in the reinforced zone. These results indicate that the recently developed concrete canvas has a better effect on restricting the slope deformation during seismic loading than the nonwoven geotextile reinforcement, and that the use of composite reinforcement could improve the seismic resistance of slopes

Real-time monitoring for road-base quality with the aid of buried piezoelectric sensors

The road-base usually deteriorate during service time due to factors such as cyclical traffic loads and road-base fouling. Currently the monitoring method for road-base quality is quite limited. This paper proposes a real-time Monitoring method for Road-Base Quality (MRBQ) based on a soil dynamic model and piezoelectric sensors buried in road-base. The soil dynamic model was extended with a piezoelectric equation to calculate the voltage in the road-base generated by a moving traffic load. Then, a model test was conducted to measure the output voltage of the piezoelectric sensors buried in the road-base. Finally, the road-base modulus was back-calculated through the soil dynamic model with the measured voltage. The back-calculated modulus was compared with the modulus measured by resonance column test (RCT) to validate this method. The unique relationship between the peak voltage and the road-base modulus at various depths was identified for different traffic load amplitudes and speeds, and the feasibility and accuracy of the MRBQ was demonstrated. This study reveals that the sensitivity of the piezoelectric sensors can reach 2 V/MPa, and the error to measure the road-base modulus is less than 20%. The proposed MRBQ demonstrates a good application potential in health monitoring of transportation facilities

Surface deformation law of mining under thick loose layer and thin bedrock: taking the southern Shandong Mining Area as an example

The surface subsidence in the thick loose layer and thin bedrock mining area in the east of China has the characteristics of large subsidence value, wide movement range and long settling time. Taking a coal mine in Southern Shandong Mining Area as an example,this paper discusses the variation rules of coal seam mining surface deformation parameters under different loose layer and bedrock thickness ratio conditions, on the basis of field measurements, using FLAC3D, and establishes a surface deformation calculation model for coal seam mining under the conditions of different loose layer bedrock thickness ratios (0.25−5.00), studies the characteristics of surface deformation, analyzed the influence of ratio of loose layer thickness to bedrock thickness on the parameters of probability integral method, and quantitatively analyzed and discussed the conditions of thick loose layer and thin bedrock from the perspective of mining subsidence. Research shows: ①Under the same mining thickness conditions,when the ratio of loose layer thickness to bedrock thickness increases, the surface deformation amount obviously increases first and then decrease, when the ratio reaches a certain limit, the ground surface deformation tends to be stabilized; ②The subsidence coefficient, the horizontal movement coefficient and the tangent of the main influence angle all increase first and then decreases, and the inflection point is 1.75,1.25 and 1.25, respectively; ③The proportion of loose bed thickness in the average mining depth has great influence on the angle of draw and boundary angle. The boundary angle and the angle of draw gradually decrease with the increase of the ratio. Based on the above research, it is proposed that the ratio of 1.25−1.75 is the critical value for the condition of thick loose bedding and thin bedrock, which provides a theoretical basis and technical reference for the prediction of surface deformation and the prevention and control of mining subsidence disasters in typical thick loose layer thin bedrock mining areas in eastern China

A two-step lineage reprogramming strategy to generate functionally competent human hepatocytes from fibroblasts

Terminally differentiated cells can be generated by lineage reprogramming, which is, however, hindered by incomplete conversion with residual initial cell identity and partial functionality. Here, we demonstrate a new reprogramming strategy by mimicking the natural regeneration route, which permits generating expandable hepatic progenitor cells and functionally competent human hepatocytes. Fibroblasts were first induced into human hepatic progenitor-like cells (hHPLCs), which could robustly expand in vitro and efficiently engraft in vivo. Moreover, hHPLCs could be efficiently induced into mature human hepatocytes (hiHeps) in vitro, whose molecular identity highly resembles primary human hepatocytes (PHHs). Most importantly, hiHeps could be generated in large quantity and were functionally competent to replace PHHs for drug-metabolism estimation, toxicity prediction and hepatitis B virus infection modeling. Our results highlight the advantages of the progenitor stage for successful lineage reprogramming. This strategy is promising for generating other mature human cell types by lineage reprogramming.</p