Dynamic Behaviors Analysis of Reduced Rotor Models with Looseness Based on the TPOD Method

The transient proper orthogonal decomposition(TPOD) method is used to study dynamic behaviors of the reduced rotor-bearing models,and the fault-free model is compared with the models with looseness fault.A 22 degree of freedoms(DOFs) rotor model supported by bearings is established.Both one end and two ends pedestal looseness of the liquid-film bearings are studied by analyzing the time history and the frequency-spectrum curves.The effects of the initial displacement and velocity values to frequency components of the original systems and the dimension reduction efficiency are discussed.Moreover,the effects of variation of initial conditions on the efficiency of the TPOD method are studied.Reduced models can provide guidance significance from the perspectives of the theory and numerical simplification to discuss the characteristics of pedestal looseness fault.

Transient Response of the Starting Rotor System with the Fault of Pedestal Looseness

The dynamic model of a pedestal looseness rotor system is built and the dynamics of the system near the resonance region is analyzed using the KBM method. Then the asymptotic method to study a dynamic system with slow-changing parameters is used to study the starting and braking course of the system. Finally, the analytical results are proved by experiment. The results can be used in the inspecting and fault diagnosis of a rotor system of this type.

Stability analysis of loose accumulation slopes under rainfall:case study of a high‑speed railway in Southwest China

The high and steep slopes along a high-speed railway in the mountainous area of Southwest China are mostly composed of loose accumulations of debris with large internal pores and poor stability,which can easily induce adverse geological disasters under rainfall conditions.To ensure the smooth construction of the high-speed railway and the subsequent safe operation,it is necessary to master the stability evolution process of the loose accumulation slope under rainfall.This article simulates rainfall using the finite element analysis software’s hydromechanical coupling module.The slope stability under various rainfall situations is calculated and analysed based on the strength reduction method.To validate the simulation results,a field monitoring system is established to study the deformation characteristics of the slope under rainfall.The results show that rainfall duration is the key factor affecting slope stability.Given a constant amount of rainfall,the stability of the slope decreases with increasing duration of rainfall.Moreover,when the amount and duration of rainfall are constant,continuous rainfall has a greater impact on slope stability than intermittent rainfall.The setting of the field retaining structures has a significant role in improving slope stability.The field monitoring data show that the slope is in the initial deformation stage and has good stability,which verifies the rationality of the numerical simulation method.The research results can provide some references for understanding the influence of rainfall on the stability of loose accumulation slopes along high-speed railways and establishing a monitoring system.

Loose Body in the Knee Joint: A Case Report

Background: Loose bodies (LBs) within the knee joint are commonly encountered during clinical practice and are frequently observed during knee arthroscopy. The primary treatment involves the removal of loose bodies;however, their complete eradication is often challenging and may not address underlying diseases, leading to persistent symptoms and the risk of new loose body formation. Aim: This case report aims to present the findings and surgical management of a 52-year-old male with an unusually large osseous loose body in the knee joint and associated pathologies. Case Presentation: The patient, a 52-year-old male, experienced recurrent episodes of severe, sudden, and painful locking of the knee joint, leading to difficulties moving. A plain MRI study was conducted to evaluate the condition of the knee joint, which revealed various degenerative changes and the presence of a loose body. Subsequently, an arthroscopic examination was performed under general anesthesia, uncovering the presence of an abnormally large loose body, as well as other pathologies including chondropathy, meniscal degeneration, and Baker’s cyst. Conclusion: Loose bodies (LBs) in the knee joint pose significant challenges and may lead to debilitating symptoms. Timely diagnosis and appropriate surgical intervention are crucial for symptom relief and the prevention of further joint damage as arthroscopic excision. Comprehensive imaging has a vital role in guiding treatment decisions and optimizing patient outcomes. In this case, the removal of the loose body improved patient outcomes and helped prevent potential joint complications.

Chemical treatment for sand production control:A review of materials,methods,and field operations

Sand production from loosely consolidated reservoirs is one of the critical issues in the oil and gas in-dustry all around the world that can cause many problems,such as erosion of surface and well equip-ment,sand accumulation in wells and operation facilities,buckling of casing in cased-hole wells and well productivity reduction.Sand production control methods include restrictive production rate,mechanical methods(slotted liner,wire-wrapped screen,pre-packed screen,frac-pack,gravel pack,high-rate water pack)and chemical consolidation that chemical method is considered for more effectiveness in sand production alleviation due to increasing formation strength in near wellbore region.This review provides an overview on the laboratory and filed operation investigations of chemical remedy for sand production.Some used chemical agents and more common laboratory tests for evaluating the chemical performance in sand consolidation are introduced in this paper.Furthermore,the results of field operations and in-jections of chemicals into the desired formation are also reported.These results show that the chemical sand consolidation is more effective in newly perforated wells which have no sand production experi-ence and have a production history of less than two years.Finally,it was concluded that the main challenges in applying this method are permeability and capillary force reduction around the wellbore and selective injection into the targeted formation layers.

A Dynamic Plunger Lift Model for Shale Gas Wells

At present,the optimization of the plunger mechanism is shale gas wells is mostly based on empirical methods,which lack a relevant rationale and often are not able to deal with the quick variations experienced by the production parameters of shale gas wells in comparison to conventional gas wells.In order to mitigate this issue,in the present work,a model is proposed to loosely couple the dynamics of gas inflow into shale gas wells with the dynamics of the liquid inflow.Starting from the flow law that accounts for the four stages of movement of the plunger,a dynamic model of the plunger lift based on the real wellbore trajectory is introduced.The model is then tested against 5 example wells,and it is shown that the accuracy level is higher than 90%.The well‘switch’,optimized on the basis of simulations based on such a model,is tested through on-site experiments.It is shown that,compared with the original switch configuration,the average production of the sample well can be increased by about 15%.

Optimization of Inducing Conditions for Loose Callus of Pinellia ternata

[Objective] The research aimed to establish the cell suspension culture system of Pinellia ternate.[Method] The petiole of Pinellia ternate was as the explant.The orthogonal test was used to study the influences of four plant growth substances（2,4-D,NAA,picloram and KT）and their mixture ratios on the formation of loose callus.[Result] The induction effect of 2,4-D and picloram on the petiole callus of Pinellia ternate was the most significant.Then,the second ones were KT and NAA.The optimal medium which induced Pinellia ternate petiole to form the loose callus was MS＋0.5 mg/L of 2,4-D＋1.0 mg/L of NAA＋1.0 mg/L of picloram＋1.5 mg/L of KT.[Conclusion] The research laid the foundation for extracting the active ingredient from the cell suspension of Pinellia ternate and producing the artificial seed.

英译《牡丹亭》选场

ＳｃｅｎｅＴｗｅｎｔｙ┐ｓｉｘＣｈｅｒｉｓｈｉｎｇｔｈｅＰｏｒｔｒａｉｔ（ＥｎｔｅｒＬｉｕＭｅｎｇｍｅｉ）ＬｉｕＭｅｎｇｍｅｉ：“Ｔｈｅｐａｌｍｌｅａｖｅｓｓｅｌｄｏｍｈｏｌｄｓｔｈｅｄｒｏｐｓｏｆｒａｉｎ；Ｔｈｅｔｉｐｓｏｆｐｅｏｎｙｓｔｏｐｓｔｈ...

Comparative experiments of gas drainage in different types of drillings

Gas drainage effect is the utmost important factor for mining speed and mining safety. It has great meaning to study the effect of gas drainage. Comparative experiment of gas drainage in different types of drillings shows that the initial rate of gas natural emission by hydraulic loosed cross drilling is 1.5 times more than that of parallel drilling, and the drilling gas at- tenuation coefficients reduces to 0.78 times, the effect of gas drainage is good. The ultimate quantity of gas drainage of parallel drilling, cross drilling, hydraulic loosed cross drilling are 859.1, 1 323.5 and 1 833.6 m3/100 m. The results of the measurement through these three kinds of drillings of 100 meters drilling is considered as following： cross drilling is 1.54 times more than that of parallel drillings, hydraulic loosed cross drilling are 2.13 times more than parallel drilling. The drainage rate of parallel drilling, cross drilling and hydraulic loosed cross drilling reached 10% to 15% in 3 months with the pre-draining time. Among these, the drainage effect of hydraulic loosed cross drilling increased by 46% than that of parallel drilling in three months.

基于Loose r-sample的网格质量保持技术

为保证虚拟手术系统中的网格质量,提出一种基于Loose r sample理论的快速表面网格重建算法。记录满足Loose r sample采样定理的点集,用以描述物体的轮廓。通过约束Delaunay方法对该点集进行三角化,标记顶点和Delaunay单元,重构新的网格。实验结果表明,该算法能够保证生成网格的质量,简化仿真复杂度。

Present Situation and Prospect of Professional Grading and Loose-leaf Purchasing of Flue-cured Tobacco

In terms of the common practice of professional grading and loose-leaf purchasing technology, the advantages of these technologies were demonstrated. The problems and proposals of the professional grading leaves purchasing model were also summarized and analyzed, so as to provide practical experiences for fur- ther promotion of loose-leaf purchasing.

Preparation of large particle rare earth oxides by precipitation with oxalic acid

The large particle CeO2 and Y2O3 were prepared using oxalic acid as precipitator. The effects of operational parameters such as stirring velocity, precipitation temperature, feeding speed, aging time, precipitation method, and calcination temperature on particle size and loose density of CeO2 were studied. Under the particular conditions, particle median size of D50≥30μm, loose density of ≥2.0 g/mlof CeO2, and particle median size of D50≥20 μm of Y2O3 were prepared. This technology had advantages of simple process, less equipment investment, ease of use, and suitability for industrialization products.

Mechanism of calcium mitigating membrane fouling in submerged membrane bioreactors

Two parallel membrane bioreactors （MBRs） were operated under different calcium dosages （168.5, 27 mg/L） to gain a better understanding of the mechanism of retarding membrane fouling by adding calcium. The results showed that the particle size of sludge flocs increased and the particle size distribution tended to be narrow at the optimum dosage （168.5 mg/L）. Calcium was effective in decreasing loosely bound extracellular polymeric substances （LB-EPS） in microbial flocs and soluble microbial products （SMP） in the supernatant at the dosage of 168.5 mg/L by strengthening the neutralization and bridging of EPS with flocs. Furthermore, the amount of CODs and CODc decreased in both the mixed liquor and the fouling cake layer on the membrane surface. In order to compare the filtration characteristics of cake layers from the MBRs with the two calcium dosages, the specific cake resistance and the compressibility coefficient were measured. The specific cake resistance from the MBR with optimum dosage （168.5 mg/L） was distinctly lower than that with low dosage （27 mg/L）. The compressibility coefficient of the cake layers under two dosages were respectively attained as 0.65, 0.91. Scanning electron microscopy （SEM） and three-dimensional confocal scanning laser microscope analysis （CLSM） images were utilized to observe the gel layer directly.

Wheel slip-sinkage and its prediction model of lunar rover

In order to investigate wheel slip-sinkage problem, which is important for the design, control and simulation of lunar rovers, experiments were carried out with a wheel-soil interaction test system to measure the sinkage of three types of wheels in dimension with wheel lugs of different heights and numbers under a series of slip ratios (0-0.6). The curves of wheel sinkage versus slip ratio were obtained and it was found that the sinkage with slip ratio of 0.6 is 3-7 times of the static sinkage. Based on the experimental results, the slip-sinkage principle of lunar's rover lugged wheels (including the sinkage caused by longitudinal flow and side flow of soil, and soil digging of wheel lugs) was analyzed, and corresponding calculation equations were derived. All the factors that can cause slip sinkage were considered to improve the conventional wheel-soil interaction model, and a formula of changing the sinkage exponent with the slip ratio was established. Mathematical model for calculating the sinkage of wheel according to vertical load and slip ratio was developed. Calculation results show that this model can predict the slip-sinkage of wheel with high precision, making up the deficiency of Wong-Reece model that mainly reflects longitudinal slip-sinkage.

Primary intestinal lymphangiectasia: Minireview

Primary idiopathic intestinal lymphangiectasia is an unusual disease featured by the presence of dilated lymphatic channels which are located in the mucosa, submucosa or subserosa leading to protein loosing enteropathy.Most often affected were children and generally diagnosed before third year of life but may be rarely seen in adults too. Bilateral pitting oedema of lower limb is the main clinical manifestation mimicking the systemic disease and posing a real diagnostic dilemma to the clinicians to differentiate it from other common systemic diseases like Congestive cardiac failure, Nephrotic Syndrome, Protein Energy Malnutrition, etc. Diagnosis can be made on capsule endoscopy which can localise the lesion but unable to take biopsy samples. Thus, recently double-balloon enteroscopy and biopsy in combination can be used as an effective diagnostic tool to hit the correct diagnosis. Patients respond dramatically to diet constituting low long chain triglycerides and high protein content with supplements of medium chain triglyceride. So early diagnosis is important to prevent untoward complications related to disease or treatment for the sake of accurate pathological diagnosis.

Strength performance of mortise and loose-tenon furniture joints under uniaxial bending moment

We determined the effects of adhesive type and loose tenon dimensions （length and thickness） on bending strength of T-shaped mor- tise and loose-tenon joints. Polyvinyl acetate （PVAc） and two-component polyurethane （PU） adhesives were used to construct joint specimens. The bending moment capacity of joints increased significantly with increased length and thickness of the loose tenon. Bending moment capacity of joints constructed with PU adhesive was approximately 13% higher than for joints constructed with PVAc adhesive. We developed a predictive equation as a function of adhesive type and loose tenon dimensions to estimate the strength of the joints constructed of oriental beech （Fagus orientalis L.） under uniaxial bending load.

Preparation and modulation of a novel thin-walled carbon foam

By foaming and carbonization processes under atmospheric pressure, a novel thin-walled carbon foam with developed foam structure was successfully prepared from loose medium component(LMC) separated from raw coal by extraction and back-extraction method. The influences of foaming time, carbonization time, and micromolecule content on foam structure were investigated by scanning electron microscope and mercury injection data. Moreover, foaming mechanism of LMC was analyzed and expounded. The results showed that spherical pores and uniform ultrathin pore walls constitute threedimensional foam structure of carbon foam and foam structure is developed with well connectivity.The effects of foaming time, carbonization time, and micromolecule content on foam structure are significant. Especially, average pore diameters of carbon foams prepared from the extracts of LMC are much smaller. With the rise of extraction rate, average pore diameter decreases and pore size distribution is more concentrated on the aperture section of 0–10 μm.

Prediction of oxygen concentration and temperature distribution in loose coal based on BP neural network

An effective method for preventing spontaneous combustion of coal stockpiles on the ground is to control the air-flow in loose coal. In order to determine and predict accurately oxygen concentrations and temperatures within coal stockpiles, it is vital to obtain information of self-heating conditions and tendencies of spontaneous coal combustion. For laboratory conditions, we designed our own experimental equipment composed of a control-heating system, a coal column and an oxygen concentration and temperature monitoring system, for simulation of spontaneous combustion of block coal （13-25 mm） covered with fine coal （0-3 mm）. A BP artificial neural network （ANN） with 150 training samples was gradually established over the course of our experiment. Heating time, relative position of measuring points, the ratio of fine coal thickness, artificial density, voidage and activation energy were selected as input variables and oxygen concentration and temperature of coal column as output variables. Then our trained network was applied to predict the trend on the untried experimental data. The results show that the oxygen concentration in the coal column could be reduced below the minimum still able to induce spontaneous combustion of coal - 6% by covering the coal pile with fine coal, which would meet the requirement to prevent spontaneous combustion of coal stockpiles. Based on the prediction of this ANN, the average errors of oxygen concentration and temperature were respectively 0.5% and 7 ℃, which meet actual tolerances. The implementation of the method would provide a practical guide in understanding the course of self-heating and spontaneous combustion of coal stockpiles.

Distributed Cooperative Control Algorithm for Multi-UAV Mission Rendezvous

Multiple unmanned aerial vehicles(UAVs)cooperative operation is the main form for UAVs fighting in battlefield,and multi-UAV mission rendezvous is the premise of cooperative reconnaissance and attack missions.We propose a rendezvous control strategy,which divides the rendezvous process into two parts:The loose formation rendezvous and the close formation rendezvous.In the first stage,UAVs are supposed to reach the specific target locations simultaneously and form a loose formation.A distributed control strategy based on first-order consensus algorithm is presented to achieve this goal.Then the second stage is designed based on the second-order consensus algorithm to complete the transition from the loose formation to the close formation.This process needs the speeds and heading angles of UAVs to reach an agreement.Besides,control algorithms with a virtual leader are proposed,by which the formation states can reach a specific value.Finally,simulation results show that the control algorithms are capable of realizing the mission rendezvous of multi-UAV and the consistence of UAVs′final states,which verify the effectiveness and feasibility of the designed control strategy.

Department of Civil Engineering, Universitas Katolik Parahyangan, Bandung, 40141, Indonesiaof loose sand with fungus

This article presents an innovative method of bio-mediated soil improvement for increasing the shear strength of loose sand.The improvement is realized by mixing the loose sand with the inoculum of Rhizopus oligosporus,a kind of fungus widely used in food industry for making Indonesian tempeh.The objective of this article is to investigate the performance and mechanism of mixing tempeh inoculum as a binding agent of loose sand particles.The inoculum dosage,water content of loose sand,and curing time were examined for identifying the increment of unconfined compressive strength(q_u)of the samples.The results showed that q_u of the treated samples increased when the inoculum dosage was elevated.It shows that 5.24%inoculum could yield 68 kPa of q_u,and 5%water content and 3 d curing time produced the maximum q_u.Moreover,the mechanism of hypha and mycelium in binding the soil particles was clearly observed using a digital microscope and scanning electron microscope.