Palembang's Light Rail Transit (LRT) rail transportation is a component of the city's rapid transitinitiative which provides 13 stations on the LRT rapid transit line, a catalyst for transit-oriented, highdensity, comparative analysis with other major cities of developed countries that have been successfulimplement this form of mass transit. mixed-use development; economical investment, providing a returnon investment for property owners, businesses and municipalities; and a catalyst for social change,improving health, the environment and community connectivity. LRT revenue comes from fare-box whichcomes from ticket sales and non-fare-box or revenue outside of ticket fares, the four main businesssectors outside of transportation services are advertising, retail, telecommunications, as well as eventsand activation.
Due to the intricacy of the challenges that arise during the execution of work, a significant amount of thework that is done does not conform to the one that was intended. Neither on time, quality, nor the price,which is something that sometimes happens overbugdet. To be successful in overcoming this obstacle, youwill need to have excellent cost, quality, and time management.Using the Value of Results Method is oneof the many ways that construction work may be handled in an efficient and straightforward manner. Thisstudy's objective is to arrive at an estimate of the time and money required to complete the project interms of how much it will effect the cost if it happens. Using the Earned Value Analysis approach is theresearch method that will be used to determine how to assess the value of the outcomes on projectperformance in terms of time and cost as well as the expected amount of time needed to finish the project.Based on the application of the results value that was studied during a period of 54 weeks, it wasdiscovered that the completion of the project would experience an acceleration of work, specifically for74.4 weeks, when the anticipated duration was 76 weeks. This was discovered after the results value wasexamined within a period of 54 weeks. In the meanwhile, when it came to the expenses of the job, it didnot come out as expected, which was Rp. 71.424.373.019. The ultimate sum of all costs associated withthe project was Rp 66.081.465.169. The fact that there is a gap of -Rp.5.342.907.850 between the overallcost of the work and the cost of the plan indicates that the project will be profitable.
Balai Pelaksanaan Jalan Nasional (BPJN) Bengkulu was born based on PUPR Regulation Number. 26 of2020. The Function is the implementation of feasibility studies, surveys, investigation, and evaluation ofplanning for the technical field of road and bridge including road safety. The Important type of survey arelongitudinal profile survey International Roughness Index (IRI), and Pavement Condition Index (PCI). TheMethod is to examined secondary data obtained from literature review and analyzed financial data (NetPresent Value, Benefit Cost Ratio, and Payback Period. The author builds four scenarios (pessimistic,medium, optimistic, and do nothing). The Benefit Cost Ratio for the scenario 1 (pessimist) is 0.33, thescenario 2 (medium) is 1.54, the scenario 3 (optimistic) is 2.82, and the scenario 4 (do-nothing) is N/A.Value of Payback Period for the scenario 2 (medium) is 5.62 years, and the scenario 3 (optimistic) is 2.79years. Based on the analysis, the decision to purchase a Hawkeye 2000 digital laser profilemeter withinBPJN Bengkulu is financially feasible as long as the hawkeye used not only for Internal, but as a source ofPNBP from client like private sector or provincial government, and distric or city governments in BengkuluProvince.
Kenten Laut is a rural locality in the Talang Kelapa District that consists largely of a swamp. Residentsrely heavily on the swamp's corrosive water for mundane concrete mixing. Researchers in this study usedswamp water and alum in the concrete recipe. Swamp water and alum were utilized as the supplementarycomponents, with the alum content of the solution varying between 2% and 4% by weight of cement. Thetest object is a cube with the dimensions (15, 15, and 15) cm and there are fifty of them.Compressive strength testing in swamp water revealed findings of 152.69 kg/cm2 for 14-day-old concreteand 251.93 kg/cm2 for 28-day-old concrete. The compressive strength of 14-day-old swamp water concretevaried between 156.16 kg/cm2 and 149.78 kg/cm2 depending on the percentage of alum added to the mix.Compressive strength values for 28-day-old concrete made with swamp water with 2%, 4%, or 6% alumare 256.19 kg/cm2, 253.97 kg/cm2, and 245.61 kg/cm2, respectively. These numbers are lower than whatwas anticipated for the K-300. Compressive strength in typical concrete drops by 20.6% after 28 days ofage, but only 14.7% after 14 days.
PDAM Tirta Musi Palembang is a government-owned enterprise engaged in water treatment services,where water that is not dirty is processed and converted into clean water that is ready and suitable forhuman consumption. The increase in annual population has an impact on the increasing growth in thenumber of customers who need clean water. However, the Water Treatment Plant (WTP) or WaterTreatment Plant (IPA) still does not provide full services to all city environments, one of which is at thePalembang City Form WTP. The source of WTP processing comes from the Borang River and intake 1 ilir.The customer population is projected to increase to 22,434 in 2023 based on Geometric analysis with acalculation of customer needs of 218.04 liters/second. The pump used at WTP Borang has a capacity of200 liters / second and uses 2 pumps, so WTP Borang can still meet customer needs. The amount of waterdischarge required during maximum days and peak hours is 239.84 liters / second and 327.06 liters /second respectively. With this situation, it is predicted that the community's clean water needs in 2023 canbe fulfilled by WTP Borang.
Four-point contact ball bearings are prone to three-point and four-point contact under actual service environment,and the complex time-varying contact characteristics lead to greater difficulty in modeling analysis and experimental research.Firstly,a mechanical model of the bearings is established to analyze the contact force and motion state.Then,the transient geometric relationship among bearing parts is analyzed by rigid body dynamics.Finally,a mechanical model is established based on Hertz contact and lubrication theory.GSTIFF I3 solver is used to obtain the state information generated by interaction between bearing components at each moment,so as to obtain the multi-point contact characteristics of the bearings.Based on the above model,the influence of rotational speed,radial load and other working parameters on dynamic contact of the bearings is analyzed.The results show that when the rotational speed is high,the bearings are prone to three-point contact under the action of centrifugal force,and the contact force of auxiliary contact pair gradually increases with the increase of rotational speed;when the ratio of radial load to axial load increases to a certain extent,the bearings are prone to four-point contact.
The GCr15 bearing steel is processed by changing the jet angle of strengthened grinding,and the salt spray corrosion test is carried out.The corrosion mechanism is analyzed by combining the corrosion kinetics curves,Fourier infrared spectroscopy,corrosion micro-morphology and three-dimensional morphology.The results show that:n value of strengthened grinding sample is 0.723 8 after salt spray corrosion test,and the and the proportion of γ-FeOOH in corrosion products is relatively low,indicating that the corrosion product layer of strengthened grinding sample has better protection performance for matrix material;with the increase of jet angle of strengthened grinding,the corrosion resistance of the sample becomes better,the surface of sample gradually changes from uniform corrosion to edge pitting,and the corrosion rate of sample gradually decreases;when the jet angle of strengthened grinding is 90°,the corrosion rate of GCr15 bearing steel is 0.060 4 mm/a,the corrosion resistance grade is 5,and the corrosion rate is much lower than that of unstrengthened grinding sample,indicating that the strengthened grinding process is able to make the workpiece have better corrosion resistance.
In order to ensure the safety and reliability of bearings during outfield fly of a helicopter,a performance and life evaluation verification technology is proposed,which simulates the actual flight conditions to the maximum extent for tail control bearings of a helicopter tail reducer under complex working conditions such as low speed and heavy load,long lubrication line and unfavorable flight attitude.By simulating the left and right flight attitude of a helicopter,a verification method is designed for ultimate capacity and durability of the bearings under unfavorable conditions.An eccentric seat is added to test device,and the shaft sleeve between tail rotor shaft and control shaft is changed to eccentric shaft sleeve,so as to approximate the actual working condition to the maximum extent.The performance and life of the bearings are comprehensively evaluated,and the reliability of test method is verified by flight test.
In response to the difficulty in grasping the changes and influencing factors of convexity of tapered rollers during oblique posture through-feed superfinishing,the working mechanism of oblique posture through-feed superfinishing is introduced,the geometric characteristics of roller-oilstone contact are analyzed,and the simulation analysis principle,method and geometric model of convexity profiling of the rollers are proposed and established,the simulation analysis flow is given,and the influencing factors of convexity are simulated and analyzed.The results show that:the skew angle of the rollers mainly affects the values and shape of convexity,and the tilt angle mainly affects the symmetry of convexity;compared with positive posture through-feed superfinishing,the oblique posture type can greatly improve the convexity values,and the two ends of convexity shape are steeper,and the convexity shape is closer to logarithmic convexity curve when the skew angle is appropriate;the thicker the oilstone,the larger the convexity value;the stronger the ability of oilstone to remove roller materials,the larger the convexity value,and the superfinished area gradually concentrates towards middle.
Bearing-rotor system is the core component that determines the working performances of motorized spindle units,and the fitting mode in mounting of bearings will directly affect the operation accuracy of the system.A dynamic model of motorized spindle bearing-rotor system is established considering thermal expansion and fitting mode of bearing inner and outer rings,the influence of interference fit of inner rings and clearance fit of outer rings on vibration characteristics of rotor is analyzed,and the correctness of the model is verified by experiments.The results show that the vibration amplitude of rotor decreases with the increase of fit interference of inner rings,and increases with the increase of fit clearance of outer rings,and the fit clearance of outer rings has a greater impact on vibration of rotor;the vibration amplitude of rotor with considering thermal expansion is smaller than that without considering thermal expansion.
A rolling bearing fault diagnosis method combining variational mode decomposition(VMD)algorithm with VGG neural network is proposed to solve the problems of large signal reconstruction errors and complex signal sources in rolling bearings.Firstly,in order to avoid the phenomenon of mode aliasing caused by improper artificial parameter settings in engineering applications of VMD,a strategy is proposed to calculate the separation coefficient using center frequency and select the optimal number of modes.Then,the energy entropy and frequency peak values of each modal component after VMD decomposition are analyzed numerically,the signals with lower energy entropy are eliminated,and each modal signal is reconstructed based on frequency peak values to obtain the fault feature vectors.Finally,a VGG fault diagnosis model is constructed to realize the fault classification of rolling bearings.The validation results of bearing vibration signals and motor stator current signals on the proposed method indicate that the VMD-VGG method can decompose these two types of fault signals effectively and has higher fault identification accuracy.
As the core components of machine tool spindles,the bearings have an important impact on machining accuracy and efficiency of machine tools.However,at present,the angular contact ball bearings for high-end machine tool spindles still rely on imports,and there is a lack of performance comparison data and application cases of the bearings at home and abroad,affecting the promotion of domestic bearings.Combined with user requirements and relevant standards,the application of grease-lubricated angular contact ball bearings 7014 in machine tool spindles at home and abroad is compared.A test scheme is designed according to assemblability,accuracy,static stiffness,temperature rise,vibration resistance and reliability indexes that t users are most concerned about.The bearing performance test,spindle bench test and machine tool cutting test after bearing installation are carried out.The comparative analysis shows that the comprehensive performance of domestic bearings reaches or approaches that of foreign bearings.
A model of hydrostatic spindle rotor system is established based on Reynolds equation and flow conservation equation,and the radial motion of the spindle is controlled by using an active single-sided thin film throttle valve as control element.The frequency domain identification method is used to identify the input and output of the system,it is found that the characteristics of the system are closer to that of second-order system in low frequency and low voltage range.The transfer function of the system is calculated using a formula to obtain the system model under small disturbances.The effectiveness of identification model is verified by designing a model predictive control(MPC)and a PID controller.The comparison between experiments and simulations show that the model can reflect the input and output characteristics of the system accurately.
The linear defects similar to cracks caused by surface treatment of bearing parts are analyzed,which is caused by waterline corrosion in electrochemical corrosion.The reason is that the acid solution stays on surface of bearing parts too long time.The waterline corrosion occurs at intersection of air,acid solution and bearing raceway.The existence of acid solution accelerates the corrosion rate and makes the linear characteristics of waterline corrosion more obvious.The waterline corrosion defects in raceway have liquid boundary contours,and their macromorphology characteristics can be used as identification criteria of defects.
The molybdenum disulfide(MoS2)and polytetrafluoroethylene(PTFE)coated solid-lubricated bearings are prepared,and the friction torque test is carried out under liquid nitrogen environment to study the changes in friction torque of the bearings under low-speed operating conditions.The results show that the friction torque of uncoated bearings under liquid nitrogen environment is higher than that under room temperature,and the friction torque of coated bearings under liquid nitrogen environment first increases and then decreases with increase of running-in time,first higher than that under room temperature and then lower than that under room temperature;the friction torque of PTFE coated bearings is higher than that of MoS2 coated bearings,but the fluctuation of friction torque is relatively small.
As the basic supporting structure of high-speed machine tools,the dynamic behavior of angular contact ball bearings directly affects the dynamic performances of high-speed machine tools.A nonlinear dynamic model of the bearings is established considering elastic deformation of rings and whirl of cages.The accuracy of the model is verified by mass center trajectory of cages and speed ratio of cages to inner rings.On this basis,the effects of wall thicknesses of outer rings on sliding of balls,whirl of cages and vibration of inner rings are analyzed.The results show that different wall thicknesses of outer rings produce different elastic deformations under external loads,affecting the sliding of balls,whirl of cages and vibration of inner rings;when the wall thicknesses of outer rings decrease,the sliding of balls intensifies,the dynamic stability of cages weakens,and the vibration of inner rings increases;when the wall thicknesses of outer rings are large,the better dynamic stability of cages and the lower vibration of the bearings can be obtained.
In order to suppress the negative influence of noise signal on fault diagnosis of bearings and solve the problem of declining accuracy of diagnosis method for bearings under noise interference in production site,a fault diagnosis method with strong robustness to noise is proposed.Firstly,the self-attention neural network is taken as main research object,the depth and width of model are analyzed,and the diagnosis effect is best when the width of model is 16 dimensions and the depth is 8 layers.Then,the necessity of position coding module in model is verified by comparative experiments.Finally,compared with CNN,LSTM,MLP,SIM and other models,the results show that the model based on self-attention neural network achieves nearly 100%diagnostic accuracy under low-intensity noise environments,and the diagnostic accuracy of the proposed model is better than that of other models under high-intensity noise environments.
The main drive bearings for large-scale tunneling boring machines generally operate under harsh environments,the reliability requirements are high and the development is difficult.There is a gap between domestic enterprises and foreign enterprises in high-load design and high-precision processing technology of the bearings,and there is a lack of comprehensive evaluation research on failure risk of the bearings in application.Combined with experience in engineering practical application of the bearings and the statistics of failure cases,the failure risk factors of main drive bearing system are evaluated through failure mode and effect analysis and fuzzy mathematical method,and the evaluation results are basically consistent with statistical analysis results,namely(arranged according to failure risk from large to small):the failure factors of the system are in order of bearing components,seals,electromechanical systems,among which the failure factors of bearing components are in order of raceway surfaces,rolling elements,inner gear rings,cages.The bearing components and seals should be focused on and protected,and the targeted maintenance measures should be taken to prevent their early failure,so as to improve the service performance and life of the bearings.
In order to accurately predict the fatigue life of oscillating bearings for beam pumping unit under actual variable load and variable speed conditions,a calculation method for fatigue life of the bearings based on variable load and variable speed conditions is proposed according to ISO 281:2007 standard and Miner linear damage theory.Taking cylindrical roller bearings for center shaft of CYJY12-4.8-73HB pumping unit as research objects,the dynamic analysis of the unit is carried out by ADAMS software to determine the oscillating load and oscillating speed of the bearings,and then the fatigue life of the bearings is calculated under actual operating conditions and compared with traditional calculation method for fatigue life of the bearings.The results show that the calculation method for fatigue life is reasonable,providing a reference for fatigue life prediction of the bearings.
The development concept and process of CAD/CAPP software are introduced for double row cylindrical roller bearings used in machine tool spindles,with Visual Basic.NET as development platform and Zhongwang CAD as graphics processing software.The main modules,workflow and operation interface of the software are introduced,and the functions are described emphatically,such as database query,optimization design of main parameters,generation of design specifications,linkage of graphics processing software,generation of design and process drawings,generation of sketches and 3D solid model.Some program source codes are also given,which can be used as reference for development of software related to other types of bearings.
