Lifting Speed Research Articles

Multiple Regression Model for the Prediction of Unconfined Compressive Strength of Jet Grout Columns

Jet grouting is one of the most widely used techniques in soil improvement because of its possibility to strengthen cut-off groundwater and provide structural rigidity with a single application by this technique. The effectiveness of the jet grouting process influenced by many factors or application parameters such as soil properties, lifting (withdrawal) and rotation speed, grout/water/air pressure, etc. Jet grout column properties (diameter and mechanical properties) are the most important parameters for designing the project. There is still no credible method that can predict the properties of jet grout columns before field application, except extreme secured empirical rules and designers generally assume the characteristics of jet grout columns by perception. This process may cause waste of time and money due to inconsistency between assumed and observed properties of jet grout columns. In the present study, it was aimed to establish a model predicting the unconfined compressive strength of jet grout columns by using multiple linear regression analysis to overcome this problem.

Dynamics of fluid bridges between a rising capillary tube and a substrate

Micro/nanolithography is an emerging technique to create micro-/nano-features on substrate. New capillary-based lithography method has been developed to overcome the limitations (e.g., the direct contact with the substrate) of existing lithography techniques including dip-pen nanolithography, nano-imprint lithography, and electron-beam lithography. The understanding of the behavior of the liquid bridge formed between a capillary tube and a substrate is essential for the recently developed capillary-based lithography method that is non-invasive to the substrate. A three-dimensional spectral boundary element method has been employed and modified to describe the dynamics of the liquid bridge. Starting with a steady-state liquid bridge shape, the transient bridge deformation is computed as the capillary tube is being lifted away from the substrate. The motion of the three-phase contact line on the substrate is taken into consideration. The computational results are validated with the experimental findings. The influences of the lifting speed of the capillary, liquid properties, and contact line slip conditions on the bridge dynamics are investigated. We conclude by computations that with a higher lifting speed of the capillary tube, the contact line radius on the substrate and the bridge neck radius reduce in a faster manner; a smaller residual droplet tends to form on the substrate if the viscosity ratio (the bridge liquid versus the surrounding medium) is larger or the substrate is more slippery to the fluids.

Research on Full-Automatic Intelligent Hydraulic Lifting Column System

In view of the current low lifting speed of the hydraulic lifting column, simple control function and other unfavorable factors, a effective theory is proposed. Such theory combining with exciting lifting technology employs the advanced PLC core chip with reliable characteristics to establish a control system. The control manners include wire mode and wireless mode. After experiment verification, the proposed control system can realize lifting function of the hydraulic column with various control mode. The proposed control system can be applied to traffic routes for safety. The purpose is to improve the traffic intelligentialize, avoid traffic accidents, and guarantee the route smooth.

Design of a Type of Lift Coating Machine

Designed a type of lift coating machine including its structure, hardware system and software system. The lift coating machine we design is a kind of wet coating equipment, which has some advantages such as lift speed, lift height, impregnate time, multilayer coating, continuous and adjustable deposition interval time. It does not need complicated vacuum environment, easy to be achieved in real life. In addition, it has no special requirements for coating matrix, which can run stably and significantly improve the precision and efficiency of coating. The lift coating machine we designed is suitable for the coating process of all solid materials such as silicon wafer, wafer, glass, ceramics, metal and so on, and it has extensive potentials in the coating market.

Energy Efficiency Analysis of Piston Type Air Compressor

In the paper,the relationship of the energy efficiency and its impact factor such as intake valve lift ,exhaust valve lift, clearance volume and rotational speed has been researched and the optimal conditions of the air compressor running was found . By adjusting the parameters of intake valve lift, exhaust valve lift, clearance volume and rotational speed, the total energy of a W-1.6/5 compressor could be reduced by 10.9%.

Experimental Evaluation of an Internally Passively Pressurized Circulation Control Propeller

The purpose of circulation control for fixed wing aircrafts is to increase the lifting force when large lifting forces and/or slow speeds are required, such as at takeoff and landing. Wing flaps and slats are used on almost all fixed-wing aircraft. While effective in increasing lift, they do so with penalty of increasing drag, weight, and control complexity. The goal of this research was to find an alternative way of pumping pressurized air to the trailing edge slot on a UAV propeller. This design called for rerouting stagnation pressure from the frontal propeller area through the inside of the propeller blades to ejection slots on the trailing edge. This allows for the forward velocity of the aircraft to drive the pressurization of the circulation control plenum passively, without additional hardware. For this study, a Clark-Y airfoil section propeller with an overall diameter of 0.609 meters was designed and tested. The comparison of the augmented to unaugmented propeller showed a 5.12 percent increase in efficiency, which is shown to act over the entire range of flight envelopes of the aircraft and is shown to be particularly beneficial at advance ratios above 0.30, normal operating conditions of propeller-driven UAVs.

Full Hydraulic and Control Systems Application in Open-Cut Mine Drill

The LWD-200B full hydraulic open cut mine drill's hydraulic system uses a variable displacement pump with load sensing constant power, load sensitive electromagnetic proportional multi-way directional valve, high torque hydraulic motor overhead direct drive rotary head, a long stroke hydraulic cylinder and steel wire rope and pulley speed lifting system, hydraulic cylinder to drive the unloading rod mechanism, hydraulic motor driving crawler, double hydraulic cylinder lifting the drill frame mechanism, a hydraulic motor driven cable winding drum, hydraulic legs leveling method. Control system adopts the control handle and the PLC control mode, with real-time data acquisition, computer automatic recognition of lithology and closed loop feedback control and GPS precise positioning function, to achieving the automatic or manual drilling, specified depth or level drilling. Through the test of practice, it is a multifunctional, fully hydraulic, which is intelligent and efficient perforation equipment.

The Effect of Lifting Speed on Cumulative and Peak Biomechanical Loading for Symmetric Lifting Tasks

BackgroundTo determine the influence of lifting speed and type on peak and cumulative back compressive force (BCF) and shoulder moment (SM) loads during symmetric lifting. Another aim of the study was to compare static and dynamic lifting models.MethodsTen male participants performed a floor-to-shoulder, floor-to-waist, and waist-to-shoulder lift at three different speeds [slow (0.34 m/s), medium (0.44 m/s), and fast (0.64 m/s)], and with two different loads [light (2.25 kg) and heavy (9 kg)]. Two-dimensional kinematics and kinetics were determined. A three-way repeated measures analysis of variance was used to calculate peak and cumulative loading of BCF and SM for light and heavy loads.ResultsPeak BCF was significantly different between slow and fast lifting speeds (p < 0.001), with a mean difference of 20% between fast and slow lifts. The cumulative loading of BCF and SM was significantly different between fast and slow lifting speeds (p < 0.001), with mean differences ≥80%.ConclusionBased on peak values, BCF is highest for fast speeds, but the BCF cumulative loading is highest for slow speeds, with the largest difference between fast and slow lifts. This may imply that a slow lifting speed is at least as hazardous as a fast lifting speed. It is important to consider the duration of lift when determining risks for back and shoulder injuries due to lifting and that peak values alone are likely not sufficient.

Resistance Training Strategies for the Clinician: Focus on the Novice Exerciser

Resistance Training Strategies for the Clinician: Focus on the Novice Exerciser

Влияние давления поджима на структурные характеристики сепарационных материалов и эффективность ионизации кислорода в электродном блоке свинцово-кислотного аккумулятора

In this article was studied pressure influence in the electrode block of the model of the lead-acid accumulator on the most important physical properties (a specific surface, pore size distribution, compression properties, speed of capillary lifting of electrolyte) of absorbent glass mat separators of the trademarks «Hollingsworth» (USA) and "Bernard Dumas"(France) and on efficiency of an oxygen cycle. It is shown that the highest compression properties separators with a high specific surface (7-10 m2/g) possess. The increase of pressure in the electrode block conducts to pores size redistribution towards decrease in a share of a pore with a radius of 10-15 microns and increase in a share of smaller pore with radius of 1-5 microns. Observed reduction of a share of a large pore explains decrease in height and speed of lifting of electrolyte with higher pressure in the electrode block. The increase of pressure in the electrode block to 50 kPa leads to decrease oxygen ionization rate on a lead electrode.

Modeling and optimal control of a wheel loader in the lift-transport section of the short loading cycle

Optimal control of a wheel loader operating in the short loading cycle is studied in order to investigate the potentials for fuel consumption reduction while maintaining acceptable production rates. The wheel loader is modeled as a system with five states and three control inputs including torque converter nonlinearities. The torque converter is modeled with no lockup enabling power transmission in both directions. The geometry of the wheel loader boom and the demanded force in the lift cylinders during lifting are used to ensure that the in-cylinder pressure remains below component's limits. The lift-transport section of the short loading cycle is divided into four phases due to discontinuities in the gearbox ratios and fuel consumption is calculated in each phase. Time optimal and fuel optimal transients of the system and the power consumption in each and every component is presented showing the dominance of the torque converter losses compared to the other components especially in the time optimal solutions. It is shown that introducing path constraints on the maximum lifting speed of the bucket due to limitations in hydraulic pumping speed moves the diesel engine operation towards higher speeds in order to maintain the lifting speed. Trade-off between fuel optimal and time optimal transients is calculated which is found to be in agreement with the results of experimental studies.

Automatic lifting system design and application of large load powered support test rig

This paper presented a design of an automatic lifting system. It is used for large load powered support and improves the old method wherein powered support lifting depends on manual control. This system applies a high accuracy gear shunt motor to match the flow for 4 lifting cylinders, and also allocates bypass throttles to realize automatic lifting. Through the displacement sensor feedback the height deviation among 4 lifting cylinders during the whole lifting process, when the deviation is up to the sitting value, the corresponding bypass throttle is operated immediately to reduce the deviation, so that the moving platform of the powered support would not be stuck. Through real application, it is shown that this system can realize automatic lifting of powered support; the lifting speed is controlled between 5 and 10 mm/s, and the final aligning accuracy is up to 1 mm.

Prediction of Peak Back Compressive Forces as a Function of Lifting Speed and Compressive Forces at Lift Origin and Destination - A Pilot Study

ObjectivesTo determine the feasibility of predicting static and dynamic peak back-compressive forces based on (1) static back compressive force values at the lift origin and destination and (2) lifting speed.MethodsTen male subjects performed symmetric mid-sagittal floor-to-shoulder, floor-to-waist, and waist-to-shoulder lifts at three different speeds (slow, medium, and fast), and with two different loads (light and heavy). Two-dimensional kinematics and kinetics were captured. Linear regression analyses were used to develop prediction equations, the amount of predictability, and significance for static and dynamic peak back-compressive forces based on a static origin and destination average (SODA) back-compressive force.ResultsStatic and dynamic peak back-compressive forces were highly predicted by the SODA, with R2 values ranging from 0.830 to 0.947. Slopes were significantly different between slow and fast lifting speeds (p < 0.05) for the dynamic peak prediction equations. The slope of the regression line for static prediction was significantly greater than one with a significant positive intercept value.ConclusionSODA under-predict both static and dynamic peak back-compressive force values. Peak values are highly predictable and could be readily determined using back-compressive force assessments at the origin and destination of a lifting task. This could be valuable for enhancing job design and analysis in the workplace and for large-scale studies where a full analysis of each lifting task is not feasible.

Development of General Embedded Intelligent Monitoring System for Tower Crane

Development of General Embedded Intelligent Monitoring System for Tower Crane

Experimental investigation of the discharge valve dynamics in a reciprocating compressor for trans-critical CO2 refrigeration cycle

The self-acting valve has a significant influence on the efficiency and reliability of the reciprocating compressor. In the trans-critical CO2 cycle, the large density and high pressure difference across the valve cause serious bending and impact stresses in the valve, offering great challenges for successful valve design. Experimental investigation of the valve dynamics is required in order to design a self-acting valve with a high efficiency and long life span for the trans-critical CO2 compressor. A semi-hermetic reciprocating compressor was developed for application in CO2 refrigeration, and a test system was incorporated into the compressor performance test rig, with a focus on investigating the dynamics of the discharge valves. With the experimental results, the movement of the valve was discussed in detail for the trans-critical CO2 compressor, allowing for the study of the thermodynamic performance of the compressor. While varying design parameters such as pressure ratio, valve lift, spring stiffness and compressor speed, the movement of the discharge valve in the reciprocating CO2 compressor was measured in order to investigate the major factors that influence the valve dynamics. The average valve speed increased from 0.71 m/s to 0.81 m/s as the discharge pressure changed from 7.8 MPa to 12 MPa. The experimental methods and results discussed in this paper could provide useful information for both valve testing and the optimization of their reliability in trans-critical CO2 compressors.

유한요소해석을 통한 자동차용 글라스의 승강성능 예측

파워 글라스 시스템의 특성은 주로 윈도우 레귤레이터의 거동 특성과 글라스 런에 의한 저항에 의해 결정되며, 시험 결과 분석을 통해 시스템의 성능을 예측한다. 본 논문에서는 시험적인 방법의 한계를 해결하기 위해, 익스플리시트 코드를 사용한 해석적 방법을 제안하였다. 해석 모델에 사용한 글라스 런은 무니-리블린 모델을 사용하여 모델링 하였고, 다양한 조건에서의 마찰 시험을 실시하여 마찰계수를 구하였다. 또한, 윈도우 레귤레이터 파트의 메커니즘은 패스트 벨트 시스템과 슬립 링요소를 사용하여 모델링 하였고, 상승 시 발생하는 전류와 하중과의 상관관계 분석을 통해 레귤레이션 메커니즘의 신뢰성을 검증하였고, 모터의 특성을 고려하여 신뢰성 있는 글라스 상승 시간을 예측하였다.

Transient Control of Electro-Hydraulic Fully Flexible Engine Valve Actuation System

Fully flexible valve actuation (FFVA) system, often referred to as camless valvetrain, employs electronically controlled actuators in place of the camshaft to drive the intake and/or exhaust valves for internal combustion engines. This system enables the engine controller to tailor the valve event according to the engine operating condition in real-time to improve fuel economy, emissions, and torque output performance. This paper presents the transient control of a laboratory electro-hydraulic fully flexible valve actuation system. Transient control of the FFVA system includes lift transient, duration transient, phase transient, speed transient, and mode transient. With constant engine speed, the valve profile is periodic in time domain and the lift, phase, and duration transients can be realized using robust repetitive control. When the engine speed varies, the period of the valve profile changes in real-time. This phenomenon poses a fundamental challenge to the transient control problem and repetitive control cannot be applied anymore. To overcome this challenge, we propose a new valve profile consisting of a periodic portion and a dwell portion with time-varying duration. Robust repetitive control is then applied to the periodic portion and proportional plus integral and derivative (PID) control is applied to the dwell portion. These two controls are switched in real-time to achieve asymptotic valve profile tracking performance. To demonstrate the effectiveness of the proposed control method, we show real-time valve-lift profiles used to explore homogeneous charge compression ignition (HCCI) combustion at different engine operating conditions.

Field study of the influence of various jet grouting parameters on soilcrete unconfined compressive strength and its diameter

0. Natures and scopesSoilcrete mass is the result of jet grouting operation, which hasspecial characteristics such as high strength, low deformability andvery low permeability. Specifications of soilcrete columns that areachieved from the jet grouting procedures from the diameter andstrength aspect depend on jet grouting parameters such as groutpressure, lifting speed, number and diameter of nozzles and c/wratio and specifications of local soil. Due to the extensive range ofeffective parameters and dependency of conclusion to local soil, it isdecided to set some trial tests in constant local soil to achieve theoptimized jet grout parameters and c/w ratio. Therefore, this paperpresents new relations between soilcrete uniaxial compressionstrength and its diameter with lifting and rotating speed, c/w ratioand grout pressure. For this purpose, air pressure, air flow, waterpressure, water flow, number and diameter of nozzles and local soilspecifications are held constant, and then the grout pressure values,c/w ratio, lifting speed and rotating speed are changed, respectively,and UCS and diameter of the columns are recorded. According tothe numerical results obtained from experiments: (1) with increasein the grout pressure, UCS (MPa) of soil and diameter of soilcreteincreases logarithmically; (2) with increase in the c/w ratio, UCS(MPa) of soil and the diameter of soilcreteincreases logarithmically;(3) with increase in lifting and rotation speed, UCS (MPa) of soil anddiameter of soilcrete decrease logarithmically.1. IntroductionJet grouting is a very attractive method for various applicationsand has been effective in many instances. One of the mostimportant advantages of jet grouting is that different types of soilscan be used in such a method. Also, the strength and permeabilitycan be improved by means of this technique. This method is asuitable substitution for common injection methods, chemicalinjection, trenching (plastic concrete and grab), piling system,foundation and/or using compressed air with the freezing methodin tunnel building. In this method, the mixture of groutingpenetrates in pore spaces, joints, cracks and voids of rock and soilstructures and optimizes the physical and mechanical character-istics of these structures, thus the penetrateability and deform-ability of layers will become low and on the other hand thestrength of these layers will be increased [1]. The jet groutingmethod is frequently used as a mean for ground improvement,especially in shield tunneling, and also in all sorts of foundationtreatment in recent years [2,3].Generally, the most important parameters that affect jetgrouting designing are soil type, mixture influx between soiland grout, exiting jet energy from nozzle, grout flow rate, rotatingspeed and lifting speed [4]. The parameters that should beassigned in the single fluid system are: grout pressure, numberand dimensions of nozzles, cement/water ratio, rotating speedand lifting speed. In the double fluid system, in addition toparameters that have been mentioned in single fluid system, airpressure and its flow rate should be assigned as well. But in thetriple fluid system, the number and dimension of water and airnozzles should be assigned in addition to the seven parametersthat have been previously mentioned [5].In discussion of the effects of soil material properties on the jetgrouting process, many researchers have described the soil’sbehavior, using the various parameters. Nikbakhtan and Osanloo[1] have shown that by increasing the grout pressure and flow, theUCS (MPa) of soil increases logarithmically. Xanthakos et al. [5]and Covil et al. [4] showed that in soft grounds and also groundswith high cohesion, effective diameter of soilcrete will decreasewith increasing the standard penetration test ‘N’ values. Yoshitakeet al. [3] suggested a nozzle with 4mm diameter to prevent it ofbeing obstructed. Covil et al. [4] and Xanthakos et al. [5] has

VORTEX EQUILIBRIA IN FLOW PAST A PLATE

Families of vortex equilibria, with constant vorticity, in steady flow past a flat plate are computed numerically. An equilibrium configuration, which can be thought of as a desingularized point vortex, involves a single symmetric vortex patch located wholly on one side of the plate. Given that the outermost edge of the vortex is unit distance from the plate, the equilibria depend on three parameters: the length of the plate, circulation about the plate, and the distance of the innermost edge of the vortex from the plate. Families in which there is zero circulation about the plate and for which the Kutta condition at the plate ends is satisfied are both considered. Properties such as vortex area, lift and free-stream speed are computed. Time-dependent numerical simulations are used to investigate the stability of the computed steady solutions.

Modelling and design of wing tip devices at various flight conditions using a databased aerodynamic prediction tool

A design study of wing tip devices at high and low speeds is described. The basis of the design study is an equivalent drag approach containing both aerodynamic drag gain and structural weight penalty. A comprehensive parameter study is carried out using a rapid aerodynamic prediction tool named Lift and Drag Component Analysis (LIDCA). Adding to an available lifting-line method a databased module for airfoil data is employed that uses results of two-dimensional flow simulations by multidimensional interpolation. Detailed validation studies of the method at high lift and high speed have demonstrated good accuracy. RANS computations of the selected wing tip designs confirm the predicted benefits at cruise condition. The results of the most effective wing tip designs are analysed at both flight conditions. Finally, options for improving the performance at take-off are suggested.