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The dynamic balance assessment during the assembly of the coordinator gyroscope significantly impacts the guidance accuracy of precision-guided equipment. In dynamic balance debugging, reliance on rudimentary counterweight empirical formulas persists, resulting in suboptimal debugging accuracy and an increased repetition rate. To mitigate this challenge, we present a multi-head residual graph attention network (ResGAT) model, designed to predict dynamic balance counterweights with high precision. In this research, we employ graph neural networks for interaction feature extraction from assembly graph data. An SDAE-GPC model is designed for the assembly condition classification to derive graph data inputs for the ResGAT regression model, which is capable of predicting gyroscope counterweights under small-sample conditions. The results of our experiments demonstrate the effectiveness of the proposed approach in predicting dynamic gyroscope counterweight in its assembly process. Our approach surpasses current methods in mitigating repetition rates and enhancing the assembly efficiency of gyroscopes. [ABSTRACT FROM AUTHOR]

The structure of the balancing mechanism for the 8ChN26/26 diesel engine is analyzed. A balancing drive with a removable housing section is proposed, so as to permit maintenance without disconnecting the alternator. [ABSTRACT FROM AUTHOR]

A method for calculating the counterweight mass of a crank-and-rod mechanism for designing a piston drive or pump is proposed. The method provides a rational combination of mass, overall dimensions, and values of wear and power loss in the bearing with maximum balance. Calculations are carried out using the MathCAD software. The optimal ranges of the parameters are given. The criterion for the best balance of the crank-and-rod mechanism is introduced to calculate the counterweight mass. Determinations of displacements, velocities, accelerations, and reaction forces are based on d'Alembert's principle in vector form for each moment in time. [ABSTRACT FROM AUTHOR]

Multistory car parking systems are a solution that brings many benefits, especially in urban areas as the number of cars increases. This study investigated the elevator of a multistory car parking system to determine the balance coefficient to reduce driving power and the influence on braking torque. The parameters were calculated based on the establishment of a planning matrix and using the calculation tools and the Taguchi method in the Minitab software. A formula was developed to calculate the braking torque of an elevator, considering the coefficient of the balancing system to ensure optimal driving power. The balance coefficient and the necessary braking torque were determined and the power was reduced by 17.5% while the braking torque was increased by 13.4% compared to the conventional method. [ABSTRACT FROM AUTHOR]

Equality of the reactive impacts along the axes in the main bearing of a crank mechanism is selected as the criterion in determining the counterweight ensuring the best balance and hence reducing the bearing vibration and wear and the mechanical losses. The influence of the mass and position of the counterweight on the reactive forces is assessed, confirming the results of simulation. [ABSTRACT FROM AUTHOR]

Copyright of Railway Construction Technology is the property of Railway Construction Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper presents the energy savings achieved by using a particular three-phase permanent-magnet motor drive control strategy in an elevator application. The proposed control methodology, based on a particular variable-amplitude variable-frequency voltage control pattern technique implemented in a permanent-magnet motor, is compared to a standard induction motor elevator case. By adopting appropriate simultaneous changes in the amplitude and frequency of the motor voltage, high speeds can be attained in conjunction with smooth starting and stopping actions involving a reduced supply current during the respective movement of the elevator. In addition, this method exhibits a high power factor with a good driving quality. The control technique introduced achieves the levelling-off of the floor and the group movement of the system using in the programmable memory a speed pattern that is generated targeting proportionality to the position of the lift. In that respect, significant energy savings can be obtained, which, depending on the type of motor implemented, can be up to 30% compared to the conventional techniques. These improvements can be attained with the appropriate handling of the applied pulse width modulation techniques. Various simulated and experimental results are given, illustrating the respective energy savings achieved with the proposed methodology. [ABSTRACT FROM AUTHOR]

Using the parametric modelling feature in Solidworks software, a three-dimensional solid model of a planetary gearbox with linear reciprocating motion of the output shaft was constructed. By conducting theoretical calculations related to the kinematics of the transmission system and combining Adams virtual prototyping simulation technology, a dynamic simulation model of the planetary gear transmission mechanism was established to analyse the motion laws and dynamic characteristics. The simulation results were compared and analysed against the theoretical calculation results, and they showed good agreement and consistency. The study also investigated the impact of counterweights on the inertia forces and moments of the output shaft in the transmission mechanism. The results indicated that adding counterweights effectively reduced the inertia impact caused by inertia forces at the start and end positions of the stroke, as well as the inertia torque caused by changes in angular acceleration during the startup and stopping phases, thereby enhancing the smooth operation of the mechanism. Additionally, different thicknesses of counterweights had varying effects on balancing the inertia forces and moments of the output shaft. The study aimed to find the optimal thickness of counterweights to achieve the best balance effect. Furthermore, the study examined the influence of different speeds of the driving gear on the inertia forces of the output shaft. The results showed that at a driving gear speed of 1500 rpm, the horizontal thrust generated by the output shaft was 63566 N, which could provide the required thrust for the rolling mill operation, and the inertia forces of the output shaft tended to stabilize.

Introduction. Rack stacker cranes are the main hoisting and transport machine for maintenance of multi-level rack warehouses. The efficiency and profitability of the warehouse depends on their efficiency. The traditional design of a rack stacker crane includes a trolley that moves along the rails on the floor of a warehouse, a column mounted vertically on the trolley, along which a carriage with a load gripping device and a load rises. The disadvantages of the traditional crane design are the relatively large mass of the trolley, the need to move it along with the column in a horizontal direction when moving around the warehouse, the relatively high energy consumption and the need to strengthen the floor of the warehouse. The crane rail tracks on the floor of the warehouse must be cleared of objects falling from above, which is associated with stopping the operation of the crane and reducing productivity.Materials and Methods. The design of a stacker crane is related to the shape of its working space. In order to improve the stacker crane, its design was developed on the basis of a jib with a counterweight, which does not require rail crane tracks. The crane of the proposed design is capable of storage in the hangars of a semicircular shape. For two warehouses: traditional rectangular and semicircular shapes, a comparative analysis of the sums of geometric distances was performed when the load gripping device moved from the loading point to randomly selected target cells. As a comparison criterion, the sum of the Cartesian distances of the load gripping device movements between the warehouse loading point and the target points, randomly selected according to the law of uniform distribution, was used. Three types of crane operation cycles were studied – simple single, double and mixed.Results. Comparative diagrams of criterion values are given. It has been established that for all types of cycles studied, to the greatest extent when working on a single cycle, the use of a crane of the proposed design with the same storage capacity significantly reduces the total geometric distance that the load gripping device must pass.Discussion and conclusions. Reducing the sum of the geometric distances of movement of the load handling device of the new crane allows to conclude that the time spent on the movements that determine the productivity of the work performed by the crane, as well as the energy costs associated with them, can be significantly reduced. Reducing energy costs is possible by replacing the translational movement of a massive undercarriage with the rotational movement of a balanced jib of a relatively small mass at the crane of the proposed design. Time is not wasted on regular cleaning of the crane tracks, associated with stopping the crane. The number of friction pairs in the proposed design of the crane is reduced compared with the traditional one.

Copyright of China Sciencepaper is the property of China Sciencepaper and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To investigate the influence of the bottom counterweight and cable distribution on hydrodynamic response of the gravity net cage, a single cylindrical gravity net cage with different cable distributions and counterweights was analysed by numerical simulation. The floating collar was simplified as a hollow ring that has the same mechanical properties as one double-row floating pipe. The influence of the current, wave and cable distribution on the floating collar motions and cable loads were investigated. Analysis results illustrated that the volume reduction coefficient of net structure and the maximum tension of cable are mainly affected by the counterweight and cable distribution, respectively. In addition, the deformation of the floating collar is mainly affected by the wave height. The cylindrical gravity net cage with the 80 kg × 32 bottom counterweight and the '*'-layout cable distribution is fit for the sea state of the Yellow Sea Cold Water Mass. [ABSTRACT FROM AUTHOR]

A macroscopic lithological study and physical (hardness, size, weight) investigations, coupled with laser-induced breakdown spectroscopy (LIBS) and X-ray fluorescence (XRF) chemical analyses of three egg- and one pear-shaped polished black stones, exposed in the library of the child home of the famous poet Giacomo Leopardi, at Recanati (Italy), were carried out. They are characterized by different sizes: two with the same weight of 16.9 kg and the two smaller ones of 5.6 kg each, corresponding to multiples of standard roman weights (drachma and scrupulum). These features and the presence of some grooves on the rock artefacts, probably for grappling hooks, suggest an original use as counterweight for the four black stones herein classified as amphibole-bearing serpentinites whose lithologies are far away from Recanati (probably coming from geological outcrops in Tuscany). The four serpentinite stones closely match with the so-called Lapis Aequipondus used in antiquity by the Romans as counterweights. Due to the presence of lead rings or iron hooks in these stones, Lapis Aequipondus were also used for martyrdoms during the persecution of Christians in the Roman period, attached to the necks of martyrs that were then thrown in the wells or attached to the ankles of hanging bodies. This is the reason why these stones are also known as Lapis Martyrum, venerated with the relative martyrs, in several churches of Rome. The four black stones investigated probably arrived at Recanati from Rome after the middle of the 19th century. In the past, Christians also called Lapis Martyrum the "devil's stones" (Lapis Diaboli). This could also be the reason for the popular belief that black stones cannot be touched by people, except those of the Leopardi dynasty. This work contributes to the cultural heritage of Leopardi's child home, as the four black stones had never been investigated. [ABSTRACT FROM AUTHOR]

Copyright of Eastern-European Journal of Enterprise Technologies is the property of PC TECHNOLOGY CENTER and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The relevance of the research is conditioned by widespread use of unregulated sucker-rod pumping units, equipped only with mechanical adjustment tools. Application of that type of units results in considerable losses of both electricity and crude oil related to machine operating in non optimal regime. To solve this problem both new and already exploited sucker-rod pumping units are equipped with means of intelligent control and monitoring, which are included within control stations equipped with frequency converter and controller. Implementation of these tools on sucker-rod pumping units control station controller requires the development of appropriate algorithms to ensure autonomous, high performance, cost-effective and reliable function of plant during all life cycle. The main aim of the research is elaboration of the algorithms for determining pumpjack balance, optimal counterbalance position and polished rod dead centres passing moment. Objects of the research are the sucker-rod pumping unit in different operating modes and pumpjack balance, defined by the counterbalance position on the crank. Methods: mathematical analysis tool of differential equations and transfer functions, computer simulation, comparison and analysis of charts and diagrams. Results. The paper considers the existing ways of pumpjack balance detection and their shortcomings. It turns out that wattmetering is the most available and fail-safe sucker-rod pumping unit condition monitoring method which does not require installation of additional external sensors. The authors have developed the sucker-rod pumping unit computer model for investigating principles and load cycles of unit operation. Based on the data obtained by simulations the authors developed the algorithm of pumpjack balance detection, which can work as sucker-rod pumping unit intelligent control station software ensuring easy control, timely service and cost reduction.

The rail in the rail-counterweight system in elevators is vertically supported along the building height by the rail brackets. In the numerical model of the rail-counterweight system, the rail-bracket assembly is modelled as a continuous beam supported by linear springs representing the rail brackets and the stiffness of the bracket is contributed to the overall stiffness of the rail-bracket assembly. To investigate the effect of the rail brackets on the seismic responses of the rail-counterweight system, a parameter named "stiffness ratio" is proposed in a rail-bracket assembly, defined as the ratio of the stiffness of the bracket to that of the simply supported continuous beam representing the rail at mid-span of an intermediate span. The stiffness of the brackets is varied by changing the stiffness ratio of the rail-bracket assembly, and the corresponding seismic responses of the rail-counterweight system are analyzed, including the maximum stress in the rail, the maximum deformation of the brackets, and the maximum displacement of the roller guide off the rail. A comprehensive analysis is conducted by considering four rail spans and three earthquake motions. The variations of the responses with the increasing stiffness ratio are dependent on the earthquake characteristics and the rail spans. The less the rail span is, the less important the effects of the stiffness ratio are. Nevertheless, the seismic responses of the rail-counterweight system generally have little change when the stiffness ratio is up to 4 and more. It is indicated that increasing of the stiffness ratio are not necessarily capable of improving the seismic performance of the counterweight system, especially when the stiffness ratio or the stiffness coefficient of the brackets is large, varying the stiffness ratio is unhelpful to change the rail-counterweight responses. [ABSTRACT FROM AUTHOR]

This paperwork shows a constructive solution for a tower crane with tilting boom assembly. The 3D model of this assembly is optimized on the basis of a Technical Calculation Method Summary Sheet. For modelling of 3D assembly Inventor 2020 design soft was used. With this soft we have the possibility to create products within a much shorter time period, therefore high productivity. [ABSTRACT FROM AUTHOR]

The results of FMECA are given for the counterweight cover-type explosion door based on its structure and working conditions. The results show that the asynchronized motion of the counterweight structure in the first generation of the counterweight cover-type explosion door results in some specific failures of the explosion door. To avoid the failure modes caused by the asynchronized motion of the counterweight structure, the counterweight structure of the first generation is improved, and the function of the synchronized loading and lifting of the second generation of the cover-type explosion door with synchronized counterweight is realized. However, some other failure modes, such as the failure of rubber seal and the freezing of condensed water should be taken into consideration to improve the reliability of the second generation. In this paper, many failure modes of the second generation are dealt with to obtain the third generation, including a completely different sealing methods which make the sealing more reliable and a drainage plate introduced to reduce the possibility of the freezing of condensed water greatly. The RPN of FMECA of the third generation is reduced significantly, and its reliability is improved greatly. The analyses show that the third generation of the counterweight cover-type explosion door is reliable and has extremely high promotion and application value. [ABSTRACT FROM AUTHOR]

The most widely used standard test methods for determining wear of the marbles are Wide Wheel (Vertical) Abrasion (WWA) and Böhme Abrasion (BA) tests. In this study, it was aimed to determine the effect of the counterweight loads applied in the WWA experiment, sample surfaces with polished and matte surfaces and different abrasive powders on the test results. In this study, a total of 48 (7x10x3cm) samples were used for the WWA tests and 24 (7x7x3cm) samples were used for the BA tests. As a result of the experiments, it was determined that the matte surfaces of the marble samples reveal more accurate results in the abrasion tests. When both artificial corundum and corundum (white fused alumina) powder are used in WWA and BA experiments, similar abrasion values are obtained on the samples. In addition, it is determined in the WWA experiment that the anisotropy of the sample is important and the counterweight affects the groove shape. [ABSTRACT FROM AUTHOR]

In this paper, a new balancing approach called "zero-power balancing" (ZPB) method is presented for a two-link robot manipulator (TLRM) whose end-effector must move on a vertical plane between two given points repeatedly. To this purpose, a simple balancing mechanism which has two adjustable degrees of freedom is presented by which the required power will be zero and the proposed method can be applied for any specific boundary conditions. In order to solve the problem, balancing problem is formulated as an optimal control problem on which the required optimality conditions were derived using the Pontryagin's minimum principle, leading to a two-point boundary value problem (TPBVP). By solving the obtained TPBVP, states, controls and the constant parameters of the counterweights were simultaneously determined. By considering the performance index as minimum effort, it was interestingly observed that the values of torque at joints vanished perfectly and identical counterweight's specifications were obtained in forward and return motions, so that the manipulator could swing between the two given points freely. Capability of the proposed method to implement the swinging motion between the two desired points was illustrated via simulation. Due to friction, air resistance, and parametric uncertainties, it was practically difficult to implement the motion repeatedly and at no power consumption as an open-loop policy, but rather two small actuators are required to control the manipulator along the optimal trajectory. Finally, an experimental set-up was developed to validate the simulation results and illustrated the efficiency of the ZPB method. [ABSTRACT FROM AUTHOR]

Although the individual threshing drum of a combine harvester was balanced on a dynamic balancing machine before it is assembled, there were still unbalances after multiple drums were assembled with the chain drive. In this paper, the double drums with a chain drive of a crawler combined harvester were selected as the research subject. The aim of this study was to develop a dynamic unbalance mode for grading chain drive double drums. Based on the dynamic unbalance characteristics of the main driven drum, the experimental research on the radial balance of the driven drum end face was carried out. It was known that the chain drive had a direct and obvious influence on the unbalanced phase of the drum. The unbalance of the drive load had an obvious effect on unbalanced amplitude of an active drum through the transfer characteristics of the chain drive. For the multi-stage transmission characteristics of a combine harvester, a step-by-step balanced grading chain drive double drum dynamic balancing method was practiced. Results showed that the unbalanced amplitude after balancing threshing drum I chain transmission mode of the combine harvester can be reduced by a maximum of 91%. Simultaneously, the unbalanced amplitude of threshing drum II can reduced by a maximum of 69.2%. The size and position of the wrap angle of the chain drive would directly affect the phase of the two equivalent unbalanced masses. [ABSTRACT FROM AUTHOR]

A three-dimensional slope stability analysis is necessary when the effects of the lateral boundary and the toe support on the load transfer can substantially change the failure mode, between thrust collapse and reverse toe sliding. Both failure modes commonly occurred throughout southeast pit of the Mae Moh mine in Thailand where unfavorable geologic structures, consisting of reversely dip-slip faults at the pit wall toe and a thin clay seam. To investigate the failure mechanisms, a series of physical models were constructed and tested, simulating a laterally confined slope on an inclined bedding plane. The stress conditions at the slope toe were evaluated using the concept of a virtual plane, based on laboratory testing. The formulations for the lateral shear resistance, using the reduction ratio, and the end resistance, derived from Rankine's passive earth pressure, were verified through comparisons with existing theories on 3D passive earth force. These proposed formulations were used to validate and predict a pit wall failure at the southeast pit. The prediction agreed well with the actual reverse toe sliding of the pit wall since the three-dimensional stability analysis had revealed that the factor of safety under the long-term strength parameters and maximum groundwater pressure head would be slightly less than one. To make the pit wall gaining more slope stability, a parametric study using the proposed formulations implied that appropriate counterweight filling with a reduction in the slope length would be a great choice for realizing the mining restraints and increasing the pit wall stability. [Display omitted] [ABSTRACT FROM AUTHOR]

Although the individual threshing drum of a combine harvester was balanced on a dynamic balancing machine before it is assembled, there were still unbalances after multiple drums were assembled with the chain drive. In this paper, the double drums with a chain drive of a crawler combined harvester were selected as the research subject. The aim of this study was to develop a dynamic unbalance mode for grading chain drive double drums. Based on the dynamic unbalance characteristics of the main driven drum, the experimental research on the radial balance of the driven drum end face was carried out. It was known that the chain drive had a direct and obvious influence on the unbalanced phase of the drum. The unbalance of the drive load had an obvious effect on unbalanced amplitude of an active drum through the transfer characteristics of the chain drive. For the multi-stage transmission characteristics of a combine harvester, a step-by-step balanced grading chain drive double drum dynamic balancing method was practiced. Results showed that the unbalanced amplitude after balancing threshing drum I chain transmission mode of the combine harvester can be reduced by a maximum of 91%. Simultaneously, the unbalanced amplitude of threshing drum II can reduced by a maximum of 69.2%. The size and position of the wrap angle of the chain drive would directly affect the phase of the two equivalent unbalanced masses.

Over the past 20 years, many long-span cable-stayed bridges with asymmetric spans have been constructed, and the counterweight is always used to balance the self-weight of the main span. This paper presents an optimization method to determine the cable pre-tension forces in long-span cable-stayed bridges considering the counterweight. This method includes: finite element (FE) model, formulation of the optimization problem and optimization algorithm. FE model is established considering the geometrical nonlinearity. The optimization problem is formulated with the objective of minimum weighted total bending energy. In addition, the constraints for the cable pre-tension forces, the bending moment of the girder and the tower, the load of the counterweight, the bearing reactions of the transition piers and auxiliary piers are all implemented in the optimization model. The optimization algorithm solves the optimization problem through the variable-step search along each design variable including the cable pre-tension forces, the load and the range of the counterweight. The efficiency and the accuracy of the proposed method are demonstrated by an application example and the results exhibit the importance of considering counterweight in the design of asymmetric cable-stayed bridges. [ABSTRACT FROM AUTHOR]

The counterweight of a propeller in a turboprop aircraft was separated during an engine run-up inspection. If this separation occurs in-flight, it may result in an accident involving serious damage or injury. In this investigation, the failed counterweight clamping assembly was studied to determine the root cause of failure. Both experimental and computational investigations were performed to explore and confirm the effects of experimentally observed anomalies on potential clamping assembly failure. Dimensional measurement of the failed clamping thread area by X-ray CT scanning revealed significant deviation from requirements in the major diameter of the thread. Fractographic and microscopic examination along with chemical analysis confirmed that the clamping bolts were pulled out due to overload stripping failure of the internal threads. Detailed computational fracture modeling utilizing the XFEM crack simulation technique provided further insight proving that thread engagement length had a significant effect on the clamping assembly failure. Based on these observations, it was concluded that the main root cause of the stripping failure was the dimensional nonconformance of the internal thread from the requirements in standard 7/16-20UNF-3B that resulted in the loss of thread engagement length. [ABSTRACT FROM AUTHOR]

Tuned mass damper (TMD) can effectively control the vibration of the long-span bridges. However, the additional load caused by installation of TMD will significantly increase the static deflection of the main girder, which greatly limits the application of TMD in the bridge vibration control. Therefore, a method for seismic control of long-span cable-stayed bridge based on counterweight-type TMD is presented in this paper. According to the structural characteristics of a long span cable-stayed bridge, the counterweight at the side-span is designed and converted into one kind of TMD to control the vertical vibration of the main girder. Taking the Sutong Bridge with a main span of 1088m and counterweight at the side span as the reference, two long-span cable-stayed bridges are designed. One is with auxiliary pier and the other is without auxiliary pier at the side span of the bridge. For each of the two bridges, the seismic responses of the key sections before and after using the counterweight-type TMD are compared and analyzed. The results indicate that when there are no auxiliary piers in the long-span bridges, the counterweight-type TMD has obvious effects on reducing the vibration of the main girder while maintaining the other functions of the traditional counterweight. And the highest vibration mitigation rate can reach 21%. However, the vibration mitigation rate is relatively low and the maximum value is less than 10% when the auxiliary piers are used. [ABSTRACT FROM AUTHOR]

Purpose: We compared physiological responses to incremental, interval, and continuous counterweighted single-leg and double-leg cycling at the same relative intensities. The primary hypothesis was that the counterweight method would elicit greater normalized power (i.e., power/active leg), greater electromyography (EMG) responses, and lower cardiorespiratory demand.Methods: Graded-exercise tests performed by 12 men (age: 21 ± 2 years; BMI: 24 ± 3 kg/m2) initially established that peak oxygen uptake ([Formula: see text]; 76 ± 8.4%), expired ventilation ([Formula: see text]; 71 ± 6.8%), carbon dioxide production ([Formula: see text]; 71 ± 6.8%), heart rate (HRpeak; 91 ± 5.3%), and power output (PPO; 56 ± 3.6%) were lower during single-leg compared to double-leg cycling (main effect of mode; p < 0.05). On separate days, participants performed four experimental trials, which involved 30-min bouts of either continuous (50% PPO) or interval exercise [4 × (5-min 65% PPO + 2.5 min 20% PPO)] in a single- or double-leg manner.Results: Double-leg interval and continuous cycling were performed at greater absolute power outputs but lower normalized power outputs compared to single-leg cycling (p < 0.001). The average EMG responses from the vastus lateralis and vastus medialis were similar across modes (p > 0.05), but semitendinosus was activated to a greater extent for single-leg cycling (p = 0.005). Single-leg interval and continuous cycling elicited lower mean [Formula: see text], [Formula: see text], [Formula: see text], HR and ratings of perceived exertion compared to double-leg cycling (p < 0.05).Conclusions: Counterweighted single-leg cycling elicits lower cardiorespiratory and perceptual responses than double-leg cycling at greater normalized power outputs. [ABSTRACT FROM AUTHOR]

To study the relationship between the fundamental frequency and pre-stress value of pre-stressed concrete beams, this paper adopted the hammering method to excite concrete beams under different pre-stress values, eccentricities and counterweights based on two kinds of methods including experiments and numerical simulation, processed and analyzed the collected mid-span acceleration of beams to quantitatively analyze the relationship between the fundamental frequency of beams and pre-stress. Research results showed that pre-stress value had little influence on the fundamental frequency of concrete beams, which was consistent with published research results. The experimental result in this paper was reliable. The experimental and numerical simulation of pre-stress value showed small relative errors. The finite element method in this paper was effective. When the eccentricity is the same, the fundamental frequency of pre-stressed concrete beams showed small changes with the increase of pre-stress value. When the prestress value is the same, the fundamental frequency of concrete beams gradually increased with the increase of eccentricity because the increase of eccentricity would improve the effective stiffness of concrete beams. When the counterweight is the same, the fundamental frequency of prestressed concrete beams showed small changes with the increase of pre-stress value. When the pre-stress value is the same, the fundamental frequency of concrete beams gradually decreased with the increase of counterweights, which was because counterweights could increase the distributed mass of concrete beams. Finally, the deflection of prestressed concrete beams under the variable load was obtained through experiments and finite element method. Experimental and numerical simulation results showed good consistency. It was also effective to use the finite element method to study the dynamic deflection of concrete beams. In addition, experimental and numerical results indicated that applying pre-stress tendons to concrete beams could play an important role in crack resistance. The research in this paper not only further verified existing results, but also provided reference for studying the fundamental frequency and dynamic characteristics of pre-stressed concrete beams. [ABSTRACT FROM AUTHOR]

This article presents a study of the potential energy efficiency improvement by means of adjusting the lift counterweight. The lift energy consumption in different counterweight set-ups is studied by employing measured lift traffic and energy consumption data from an office building in Finland. Overall, dimensioning the counterweight based on traffic analysis is one of the fastest and most cost-effective means of improving the energy efficiency of lifts. The results from the building imply, however, that with a relatively constant loading throughout the day, the continuous adjusting of the counterweight provides limited energy savings compared to systems where the counterweight is sized according to the average load. Nevertheless, active adjustment of the counterweight size may provide considerable savings in lift systems if there is a wide variation in the car loading between the hours of the day. Furthermore, reducing the counterweight potentially improves the ISO 25745-2 energy efficiency classification of the lift, thus increasing the product attractiveness in the market.Practical application: This article presents practical approaches to analysing the energy consumption of counterbalanced lifts. The modelled results can be used to optimise the mass of the counterweight in order to achieve considerable energy savings in the actual or expected traffic profile. [ABSTRACT FROM AUTHOR]