An innovative deformation coordination method for analyzing distortion effects on box girders.

A deformation coordination method is proposed in this study to account for the distortion effects on a box girder. The differential equation for distortion in vertical web box girders is derived based on the deformation coordination condition of the distortion angle, considering both external loads and internal forces. Subsequently, a comparative analysis is conducted to explore the similarities and differences between the differential equations derived from the proposed deformation coordination method, the plate element analysis method and the total potential energy variation method. The accuracy of the proposed approach is verified through bench-scale tests and numerical simulations. The findings indicate that the derived governing distortion differential equation and distortion attenuation coefficients in the proposed method align with those obtained from the plate element analysis method and the total potential energy variational method, which enhances the applicability to allow for the distortion equations to be obtained simply by calculating the distortion displacements. The analytical findings regarding the distortion warping normal stresses on the cross-sections of the box girders demonstrate favorable correspondence with the experimental results, displaying an acceptable error ranging from - 0.3% to 5.4%. Moreover, the peak of distortion warping normal stresses on the mid-span cross-section increases with higher span-to-depth ratios and height-to-thickness ratios of the web. Consequently, augmenting the thickness of the box wall proves to be an effective means of reducing the distortion effect in box girders.

Establishment and application of the environment evaluation model for beneficiation plant.

In order to evaluate the beneficiation plant environment in a more scientific and reasonable way, this paper took the workshop environment of the beneficiation plant as the research object. This paper divided the beneficiation plant into 7 evaluation units according to its functions. The evaluation indices are dust, noise, light environment, microclimate, benzene, toluene and xylene. This paper combines the G1 method and the entropy weight method to evaluate the weight of each evaluation index, the element extension model of the concentrator working environment is established by the element analysis method, and the matter element analysis method is used to establish an evaluation index system of a beneficiation plant in East China. The results show that the evaluation level of the breaking workshop and the auxiliary facilities are unqualified, the auxiliary facility is qualified, the culling workshop, culled yard and accessory building are medium, the screening workshop and grinding workshop are good.

A new way to calculate productivity of five point well pattern at high water cut stage.

This paper presents a new way to obtain the instantaneous productivity of five point well pattern in low permeability reservoirs at high water cut stage. Different from the traditional analysis methods or semi-analytical methods, this paper takes the distribution of remaining oil into consideration, and uses the successive steady state method and 'six step' to obtain the numerical solution, which is accurate and simple. The effects of parameters including fracture length (the injection well and the production well) and pressure difference between the injection well and the production well were investigated in detail, which have a significant impact on instantaneous productivity. The advantage of the numerical solution is able to understand productivity at different times, and easy to incorporate well spacing and the optimal pressure difference. The amount of computation that this new method needs is very small, and it can also compute quickly and efficiently.

Simulation of three surgical techniques combined with two different bone-borne forces for surgically assisted rapid palatal expansion of the maxillofacial complex: a finite element analysis.

Surgically assisted rapid palatal expansion (SARPE) is a common treatment to correct transverse maxillary deficiencies. Finite element analysis was simulated for six designs of SARPE based on a computed tomography scan of a human skull: median osteotomy with palatal (type A) or alveolar ridge (type B) bone-borne force, additional lateral osteotomy with palatal (type C) or alveolar ridge (type D) bone-borne force, and additional pterygomaxillary separation with palatal (type E) or alveolar ridge (type F) bone-borne force. The transverse expansion was about 1.0mm. The distribution of von Mises stress and the displacement were evaluated. The largest stress distribution was after types A and B, followed by types C and D, and finally types E and F. Displacement increased simultaneously. Palatal bone-borne forces (types A, C, and E) led to higher stress distributions in the midface and maxilla, but to a more parallel expansion compared with alveolar ridge-borne forces (types B, D, and F). The largest bony displacements at the midpalatal suture were anterior in all models. Increased weakening of the bony pillar of the facial skeleton and the use of palatal bone-borne forces leads to a decrease in stress distribution in the midface and to a more parallel transverse expansion of the maxilla.

[Finite element study on calcium phosphate ceramic screw implanting after removing dynamic hip screw].

Objective: To investigate the validity of improving the femur's mechanical characteristics by implanting calcium phosphate ceramic screws after removing dynamic hip screw (DHS). Methods: The three dimensional finite element model of the femur was built based on the CT scanning of a normal male volunteer. Then the models of the femur with and without DHS were established. According to calcium phosphate ceramic screws with porosity and apparent elastic modulus, 80% and 0.1 GPa were set as group A, 50% and 1.0 GPa as group B, and 30% and 1.5 GPa as group C. Von Mises stress distribution and maximum stress were recorded when the joint was maximally loaded in a gait cycle. Results: The Von Mises in normal femoral shaft was uniform; no phenomena of stress concentration was observed and the maximum stress located at the joint load-bearing site of the proximal femur. The stress concentration was observed in the femur without DHS, and the maximum stress located at the distal femur around the screw hole. By comparing several different calcium phosphate ceramic screws, the stress distribution of group B was similar to normal femur model, and the maximum stress located at the joint load-bearing site. The other screws of groups A and C showed varying degrees of stress concentration. Conclusion: Implanting calcium phosphate ceramic screw can improve the mechanical characteristics of the femur after removing dynamic hip screw, and the calcium phosphate ceramic screw with 50% porosity and 1.0 GPa apparent elastic modulus is suitable for implanting.

Experimental study of scoring model for liver cirrhosis diseases / 第二军医大学学报

Objective: To establish a scoring model for liver cirrhosis disease (SLCD) in experimental rats, so as to provide evidence for early clinical prevention and treatment of liver cirrhosis diseases. Methods: The liver cirrhosis model was induced in rats by composite factor method. The damages of hepatic tissues and the changes of serological liver function were observed in different phases of the rat liver cirrhosis model. The SLCD formula was obtained using the Master-Element Analysis method. Results: The experimental liver cirrhosis model was successfully established in rats. The experimental rat SLCD and SLCD formula were successfully constructed using the following 6 parameters, the age, total bilirubin, albumin, prealbumin, prothrombin time-international normalized ratio, and serum creatinine. The score was expressed as the R value, which gradually decreased with the aggravation of lesion and fibrosis. R=1: the liver tissue was normal; 0.702 ≤ R < 1: there were inflammatory reaction, focal degeneration and necrosis in the liver; 0.542 ≤ R < 0.702: there was fibroplasia in the liver; 0.352 ≤ R < 0.542: pseudolobules were formed, and it was in the liver cirrhosis stage; and R<0.352: it was in the later stage of liver cirrhosis. Conclusion: The SLCD model can sensitively and accurately display the liver impairment and liver function reserve during experimental liver cirrhosis in rats. It may help the early prevention, diagnosis and treatment of the cirrhosis diseases if relevant clinical evidence is obtained.