Construction Parameters Research Articles

Modeling the residential buildings erection of large-sized blocks

Introduction. the development analysis of domestic residential building construction of volumetric blocks, starting from the 60s of the twentieth century to the present time, is given. It is noted the innovative nature of the transition from low-
 volume blocks to large-sized blocks of high and full factory readiness. The problems that have arisen in this case are indicated, of which one of the most acute is the determination of organizational and technological parameters for the construction of residential buildings.
 
 Materials and methods. the role of organizational and technological parameters of the objects’ construction is described — the duration of construction and its stages, the complexity of work, the number of workers. The content of the timing carried out by the MonArch Group of Companies for the installation of large-sized volumetric blocks of a four-story residential building in Yakovlevo–2 village (New Moscow) is revealed. The main installation operations are analyzed with an indication of the time spent on each floor and the roof arrangement.
 
 Results. based on the final results of the timekeeping materials generalization, three estimates of the duration of a building construction of large-sized blocks are proposed — pessimistic, satisfactory, optimistic. The found dependences “duration of building construction — the number of large–sized blocks installed taking into account the roof arrangement” are revealed with the corresponding calculation formulas. The formula for calculating the labor intensity of installers work and crane maintenance workers is also given.
 
 Conclusions. the prospects for the innovative technology development for the construction of residential buildings of large-sized blocks are substantiated, provided that capital investments are allocated and the efforts of research and design organizations are combined to comprehensively solve the problems that have arisen. To solve the problematic tasks of determining the indicators of organizational and technological parameters of buildings construction of large-sized blocks, an approach and methods for assessing the duration of construction and the complexity of installation work on the assembly of buildings are proposed.

Numerical analysis of the influence iron type on Von Mises Stress and safety parameters for compost processing machine frame construction

The installation of other engine parts, such as the engine, transmission, shaft, blade, and cover, includes the engine frame. The engine frame must be developed and constructed with the strength to support other components. The building of the waste processing machine frame with variants of square tube type and angle bar type will be analyzed in this study, with a focus on the analysis of von Mises’s stress and safety aspects. Using Solidworks software, finite element analysis is the research methodology used. The examination of the waste processing machine’s frame modelling using square tubes and angular bars yielded maximum von Mises stress values of 3.77e+7 N/m2 and 3.162e+4 N/m2, respectively. The maximum deformation values for the square tube iron and angular bar used in the modelling analysis of the waste processing machine frame are 2,499e+1mm and 9,725e+1mm, respectively . and 8.5 and 1 is the required minimum safety factor value for modelling the frame of a waste processing machine made of square tube iron. The safety factor value of 2-3 is the primary criterion for a suitable design. It is safe and advised to utilize the waste processing machine frame made of square tube iron for this purpose.

Study on fracture conductivity under dynamic sand laying mode

The existing API static sand laying fracture conductivity evaluation experiment ideally believes that the proppant is evenly and statically laid in the fracture, without considering the actual fracturing conditions, the proppant migrates along the fracture and leaks into the formation. In order to more truly simulate the actual fracturing conditions, the experimental study of fracture conductivity is carried out by using the dynamic conductivity testing device, which is closer to the field reality than static sand laying. The parameters of the indoor dynamic sand laying diversion experiment are determined by the similarity criterion and the indoor fracturing fluid rheology experiment. The orthogonal experiment and the shear support fracture dynamic diversion experiment are designed to study the effects of pumping displacement, fracturing fluid viscosity and construction sand ratio on the dynamic sand laying diversion ability, and optimize the on-site construction parameters. The experimental results show that increasing the construction displacement, sand ratio and selecting the appropriate fracturing fluid viscosity have a positive impact on the fracture conductivity of dynamic sand laying support, among which the sand ratio has the greatest impact. Under the condition of effective closure stress of the reservoir, the natural non sanding shear fracture and the dynamic paving shear fracture with 12% sand ratio have no conductivity, which is difficult to meet the requirements of field production. When the 1-3 mm shear joint is dynamically paved with 18% sand ratio and the closing pressure is 30-70 MPa, the conductivity is positively correlated with the sand concentration, but it is nonlinear with the shear dislocation. The shear joint pump injects 18% proppant with sand ratio, which can support the fracture under high closing pressure and provide conductivity. It is necessary to appropriately increase the pump injection ratio of more than 18% sand ratio according to the proportion of on-site shear cracks to effectively support shear cracks.

Вплив конструктивних параметрів термоплати на гістерезис за тепловим навантаженням

The contact heat exchangers designed to remove heat from the cooled devices are used in mechanically pumped two-phase loops of thermal management systems for ground and space applications, a thermoplate (heat sink). After the device is turned on, it may overheat abnormally during the process of reaching a stationary operating mode. Overheating is associated with the phenomenon of thermal load hysteresis during the onset of boiling, the transition from single-phase convection to developed boiling in the evaporator of a heat sink material. This work studied the influence of the construction parameters of thermoplate on the hysteresis phenomenon at the integral level. For this purpose, a thermoplate testing methodology was implemented, which includes experiments with slow (quasi-stationary) and quick heating after turning on the device immediately at full power. Overheating of the device is possible during both "slow" and "quick" heating. The maximum overheating in the experiments performed was ~18 K. Such overheating can pose a danger to the reliability of the device. The study was performed with ammonia as a coolant on 5 models of thermoplate that differ in evaporator channel roughness, length, material, longitudinal thermal conductivity, the heat capacity of the structure, etc. The danger of overheating the device is also determined by the maximum thermal load at which the device is operated. The following conclusions were made: the greatest influence on the hysteresis parameters is the value of the evaporator channel surface roughness. Increasing the roughness reduces the risk of overheating the device, and changes the nature of the "boiling curves" in the thermoplate; an increase in the length and longitudinal thermal conductivity has a favorable effect on reducing the risk of overheating; the evaporator surface is made of aluminum alloy instead of stainless steel, which makes hysteresis impossible; in the case of rapid heating of the thermoplate, the maximum heat flux at steady-state has an ambiguous effect: with its increase, overheating due to hysteresis first increases, and in the case of further increase, it decreases and may disappear altogether. A significant increase in the maximum heat flux compared to the heat flux at the beginning of boiling reduces the danger of hysteresis affecting the overheating of the device. The results of this work provide recommendations on how to avoid the dangerous overheating of the device due to the hysteresis phenomenon.

RESTRICTED SELECTION INDEX FOR GROWTH TRAITS OF SHAMI KIDS

A Restricted Selection Index was constructed to genetically evaluate animals using a dataset composed of body weights of Shami kids at the ages of birth, weaning, and 6-month. The variance-covariance matrix (VCV) was generated and used to estimate genetic parameters for the index construction after adjusting the fixed effects; year, birth month, kid sex, type (single, twin or triplet) of birth, doe age, weights at kidding (KW), birth (BWT) and weaning (WWT) as covariates. General Linear Model and Restricted Maximum Likelihood methods were used to estimate BLUE for fixed effects and variance components for random effects, respectively. BW was 3.6 ± 0.017, WW 16.8 ± 0.10, and weight at 6 months (MWT) was 26.7 ± 0.21 Kg. With the exception of buck origin and doe age, all tested factors significantly affected growth traits. Heritability for BWT, WWT, and MWT was 0.70 ± 0.10, 0.32 ± 0.075, and 0.41 ± 0.12, and repeatability was 0.78, 0.35, and 0.47, respectively. Genetic and phenotypic correlations were positive and significant between BWT and WWT, and between WWT and MWT. The restricted selection index constructed for increasing weights at MWT and WWT with restriction on BWT yielded a strong correlation coefficient (rIA) between the genetic merit and the index at 0.54 (p<0.01).

Electric Cable Construction Parameter and Its Potential to Foresee the Cable Fire Properties

A cable parameter related to the volume of effective non-combustible content, Ω, is proposed, which depends on the ratio of non-metallic, non-combustible component volume to non-metallic, combustible component volume, and the effective area of heat transfer within the cable during the combustion process. The correctness of the proposed cable parameter for circular cables is confirmed by tests and the determination of Spearman's correlation. High Spearman's correlation factors (close to -1) were obtained for total heat release and total smoke production as a function of the Ω cable parameter. The Ω cable parameter might be used in selecting cable samples for large geometric-scale fire testing within the same cable family.

Impact of subway shield tunnel construction on deformation of existing utility tunnel

In recent years, the development of urban underground space in China, especially the construction and operation of subway tunnels, has greatly relieved the pressure of urban traffic. Due to the imperfect planning of urban facility, many subway tunnels have to be built under the existing utility tunnels (pipe galleries). Nevertheless, shield construction of subway tunnel has a great adverse impact on the deformation and safety of the existing pipe gallery. Therefore, this paper takes Xi’an Metro Line 2 as an example, and studies the safety depth for subway tunnel shield construction under different regional conditions in Xi’an through numerical simulation. The results show that the deformation of the existing pipe gallery and its influence range decrease with the rising buried depth of the double-line subway tunnel when the soil properties are good. For example, in the loess tableland area, when the buried depth of the subway tunnel is greater than 12 m, the settlement deformation of the pipe gallery basically meets the control standard. When the soil properties are poor or the soil properties vary greatly, the subway tunnel excavation has a great impact on the safety of the pipe gallery. For example, in the first-level alluvial fan area with sand layer, when the buried depth of the subway tunnel is less than 24 m and more than 12 m, the deformation standard cannot be satisfied. In addition, in the first-level alluvial fan area with sand layer, the lower soil layer should be treated or the construction parameters should be optimized before the excavation of subway tunnel. The research results can provide reference for similar engineering construction.

Exact Formulation for the Curvature of Gothic Arch Ball Screw Profiles and New Approximated Solution Based on Simplified Groove Geometry

The correct evaluation of the curvatures of ball screw grooves allows the accurate design of the constructive parameters of this mechanism and enhancing its performance. The formulation commonly used in the literature, however, refers to ball bearing geometry, ignoring the shape of the section’s profile and the helix angle. In this paper, the exact formulae for calculating the principal curvature radii of the screw shaft and the nut grooves are analytically derived and presented. These equations, obtained through a rigorous differential geometry approach, consider the helix angle and a gothic arch profile. An approximated formulation is proposed simplifying the exact solution under the assumption of a circular groove profile. These new simple formulae accurately reproduce the exact curvature radii values with a mean relative error of approximatively 0.51% and 0.40%, respectively, for the screw shaft and nut grooves, against the value of more than 50% obtained by using the literature formulae for common off-the-shelf ball screws, especially those with high helix angles. Furthermore, they allow a computational time saving of 98%, making them suitable for being incorporated in high-fidelity dynamic models of ball. Finally, two MATLAB functions are provided to easily evaluate the complex curvature exact solution.

Influence analysis and relationship evolution between construction parameters and ground settlements induced by shield tunneling under soil-rock mixed-face conditions

This study investigates the influences of the key shield parameters on tunneling-induced ground settlements considering the dynamic excavation process. The advanced machine learning method in conjunction with principal component analysis is applied to evaluate the nonlinear relationships between ground settlements and the multi-parameters in the soil-rock composite ground. Considering the interaction among multi-factor, the nonlinear relationships of excavation characteristic parameters are developed by the correlation analysis to quantify shield machine performance in the mixed ground. Predictions on ground settlements in the soil-rock mixed-face are conducted in good agreement with the in-site measured data from the Nanjing Metro Line No. S7 tunnel. The implementation effects of the Light-GBM based model are evaluated by RMSE and R2. Subsequently, the influence weights of the most important influencing factors are ranked to control the parameters, which will be beneficial to optimize the excavation scheme during the dynamic construction process. Finally, the empirical formulas are proposed according to the high-correlation parameters as well as the measured datasets by the nonlinear multiple regression process, which can provide guidance for shield tunnel operation in the soil-rock composite ground.

Iterative Horizontal Method of Slices for Global Stability of Slurry Trench in Layered Cohesive-Frictional Soils

This paper presents an iterative horizontal method of slices (iterative HMS) for the global stability analysis of a slurry trench in layered cohesive-frictional soils. The iterative HMS differs from existing HMS models in terms of the assumptions on interslice forces. Preceding HMS techniques postulate that normal interslice forces can be evaluated from overburden pressures, which can lead to the violation of failure criteria along interslice boundaries. The iterative HMS ensures that a limit equilibrium system is established without violating the failure criterion throughout the entire soil mass. This is achieved by iteratively adjusting interslice forces by means of enforcing the failure criterion for the aforementioned problematic slice boundaries violating the failure conditions. The performance of the iterative HMS is evaluated in example problems of a slurry trench in uniform clayey soils and cohesive-frictional strata. The results are compared against solutions obtained using finite-element limit analysis (FELA) and a shear strength reduction FEM (SSRFEM). This comparative analysis shows that the adjustment in interslice forces is important for reasonably assessing trench stability conditions. A parametric analysis is performed by using the iterative HMS to show under what trench construction parameters the adjustment of interslice forces cannot be neglected in the stability analysis of a slurry trench.

A multistage model for rapid identification of geological features in shield tunnelling

Decision-making on shield construction parameters depends on timely and accurate geological condition feedback. Real-time mastering of geological condition around the shield during tunnelling is necessary to achieve safe and efficient construction. This paper proposes a Rapidly Geological Features Identification (RGFI) method that balances the model's generalizability and the accuracy of geological identification. First, a k-means algorithm is used to redefine the stratum based on the key mechanical indexes of strata. An XGBoost model is then used to determine the stratum composition of the excavation face based on the tunnelling parameters. If the result is compound strata, a deep neural network with an attention mechanism is used to predict the percentage of each stratum. The attention mechanism assigns weights to the features of the tunnelling parameters according to the stratum composition. The simulation results in the interval between Qian-Zhuang and Ke-Ning Road of Nanjing Metro show that the method can effectively determine the geological conditions on the excavation face. Furthermore, the method was used in the Hangzhou-Shaoxing intercity railroad tunnel project, where the 'ZhiYu' self-driving shield was used for tunnelling control. It helped the 'ZhiYu' shield to adjust the construction parameters quickly and improve the safety and quality of the project.

The Influence of Pile-Beam-Arch Construction on the Stratum and Station Support Structure

The PBA construction method is suitable for urban subway construction in situations with dense traffic and many surrounding buildings and can effectively reduce surface disturbance and control surface subsidence. Based on field-measured data, this study creates numerical finite element models of 3D stratum-structure, studies the influence of each process conversion on the subsidence of the ground surface and the force of the station supporting structure during the construction of the PBA station, and clarifies the optimal construction parameters. The research results show that the consistency between the field monitoring data and the simulation data is more than 80%, which verifies the correctness of the model. It is concluded that the formation of the pile-beam-arch is the main part of the supporting structure and that digging the pilot tunnel and the formation of the beam arch are the control factors of surface settlement. Based on this, the best sequence of pilot tunnel excavation and arch buckle of the two-story two-span station is obtained, and the optimal pilot tunnel excavation scheme of first the middle and then the side, first the upper and then the lower, and the best arch buckle scheme of the synchronous arch buckle on both sides is determined. The results of the research can serve as a guideline when selection the construction parameters for similar PBA stations.

Energetic optimization and local stability of heliothermal plant models under three thermo-economic performance regimes

Solar power plants have the advantage of not producing greenhouse gases into the atmosphere. In their operation, some design and construction parameters can be identified for improving their performance. In this work within the context of Finite-Time Thermodynamics (FTT), we analyze a Müser–Curzon–Ahlborn heat engine model by maximizing economic-objective functions which not only provide optimal operation modes, but also they can reduce the energy dissipated in the form of heat towards the atmosphere. In our thermo-economic study we take into account both investment as well as operation and maintenance (O&M) costs. From operation data of three commercial tower-power plants: Eurelios, Gemasolar and Ivanpah, we find optimal values of solar concentration (Ci) for each economic-operation regime, accounting for the effect of internal irreversibilities (through a lumped parameter R). The Ci-values that we found are in the range of current reported values for the three power plants aforementioned. Besides, we present a local stability analysis for the three aforementioned solar plants and we show that for large size plants, disturbed isothermal branches return faster to their respective steady states, in less dissipative regimes, (e.g. the ecological regime).

LNG point supply of villages and towns in China: Challenges and countermeasures

Liquefied natural gas (LNG) point supply is one of the most flexible and convenient methods advocated by China for distributing energy to end-users such as towns and villages where it is difficult or uneconomical to construct gas pipelines. This study sorts out the advantages and challenges and designs the optimization model for LNG point supply in China based on a mixed-integer linear programming (MILP) model. In this model, the goal of optimization is to minimize economic and environmental costs in the construction and operation stages. By optimizing location-allocation, gas storage capacity, vaporization capacity, equipment selection, and pipeline distribution, the model meets the fluctuating seasonal demand for natural gas. This model design uses the actual construction and operation-related parameters of the vaporization station and pipeline, and applies the model to four different types of towns. Through sensitivity analysis, this study finds that the sensitivity of construction cost is relatively high.

Two-mirror aerial mapping camera design with a tilted-aplanatic secondary mirror for image motion compensation.

The optical compensation method is a promising method to compensate the image motion by driving the optical element of the system. However, the tilt motion of the optical element could induce the degradation of the image quality. Based on the Nodal Aberration Theory (NAT), this paper proposes a novel optical image motion compensation design with a secondary tilt-aplanatic two-mirror optical system (STATOS), which achieves the insensitivity on the image quality of the optical system. First, the properties of coma-free pivot point depending on the location of stop at primary mirror or secondary mirror have been analyzed respectively. Then the calculating method about construction parameters in terms of STATOS is developed. Further, the maximum tilt angle of secondary mirror could be solved using NAT under ordered specific restriction. Finally, a prototype is designed with SM-tilting result of MTF value maintain above 0.32 at the cut-off frequency of detector, where the principal distance could remain stable and the changed distortion is better than 0.03%. A test flight has been carried out to prove the desired results and feasibility of STATOS used in an aerial mapping camera.

An Experimental Study of Stem Transported-Posture Adjustment Mechanism in Potato Harvesting

Potato stem removal is one of the critical technical problems of potato mechanized harvesting; it directly affects the quality of potato harvesting and potato storage. There have been several studies on potato stem removal mechanisms. In practice, however, it was found that the potato stem removal rate was greatly influenced by the posture of the stem before it entered the removal mechanism. In this study, we designed a potato stem posture adjustment mechanism consisting of elastic curtains. A test rig was built to investigate the effect of curtain height, curtain width, and curtain suspension height on potato passage rate and potato stem removal rate. The Box–Behnken design (BBD), combined with the response surface method, was used to conduct the test. The optimal construction and installation parameters for each elastic curtain were determined as 278.93 mm for the curtain height, 20 mm for the curtain width, and 260 mm for the curtain suspension height. The predicted values of potato passage rate and potato stem removal rate under the optimal parameters were 92.36% and 82.83%, which were consistent with the validation test results. Based on the optimization results, a rigid-flexible coupled simulation model for a potato stem transported-posture adjustment process based on Abaqus and Adams was constructed. The maximum impact of the elastic curtain of the stem posture adjustment mechanism on the potato stem was 15.91 N and caused the stem to spring back. The projection angle β′ of the stem posture angle in the xoz plane before posture adjustment was 19.07°, and the β′ of the stem after posture adjustment was 87.18°. At this time, the stem was basically parallel to the rod of the separating sieve and had a high probability of falling from the gap of the bar to complete the removal of the stem. Overall, the stem transport position adjustment mechanism effectively adjusted the stem transported posture and improved the stem removal rate in potato mechanical harvesting.

Optimizing construction parameters for fractured horizontal wells in shale oil

Shale oil is mainly extracted by fracturing. However, it is difficult to determine the optimum construction parameters to obtain maximum productivity. In this paper, a fuzzy comprehensive production evaluation model for fractured shale oil horizontal wells based on random forest algorithm and coordinated principal component analysis is proposed. The fracturing parameters of the target wells are optimized by combining this model with an orthogonal experimental design. The random forest algorithm was used to calculate the importance of data sample factors. The main controlling factors of the production of fractured horizontal wells in shale oil were obtained. To reduce the noise of the sample data, principal component analysis was used to reduce the dimensions of the main control factors. Furthermore, the random forest algorithm was used to determine the weight of the principal components after reducing the dimensionality. The membership function of the main control factors after reducing dimensionality was established by combining the fuzzy statistics and assignment methods. In addition, the membership matrix of the effect prediction of fractured horizontal wells in shale oil was determined. The fuzzy comprehensive evaluation method is used to score and evaluate the effect of fractured horizontal wells. Combined with the orthogonal experimental design method, the optimized parameter design of a fractured horizontal well considering the comprehensive action of multiple parameters is realized. After construction according to the optimized parameters, production following fracturing increases significantly. This verifies the rationality of the optimization method that is proposed in this paper.

Spatial-temporal fusion network for maximum ground surface settlement prediction during tunnel excavation

The maximum ground surface settlement prediction is a complex problem as the settlement depends on plenty of intrinsic and extrinsic factors. To obtain the approximate range of the settlement, a hybrid prediction dataset including the geological and construction parameters is built using spatial and temporal series according to the sampling methods. The settlement prediction task is transformed into a multi-modal and multi-variate series prediction task. Hence, a spatial-temporal fusion network (STF-Network) is proposed. The spatial-temporal fusion mechanism is firstly designed to establish the spatial-temporal fusion map, which makes spatial and temporal series interact earlier. Then, the 3D residual unit structure is designed to capture the features of temporal series and spatial-temporal fusion map, and two fully-connected layers are established to capture the spatial structural information. Finally, the final output is merged by the three components. The experimental results for STF-Network demonstrate the superiority over state-of-the-art methods.

Parameters of construction, positioning, orientation and those of adequate operation of a solar distiller in the south east of Algeria

Parameters of construction, positioning, orientation and those of adequate operation of a solar distiller in the south east of Algeria

Optimization Study on Underground Excavation of a Newly-Built Tunnel Passing Underneath an Existing Subway Station in Zero Distance and the Construction Parameters

With the networked development of subway tunnels, the approaching construction of a newly-built tunnel will bring great threat to the safety of the existing tunnels. In this paper, taking Nanjing Subway Line 5 Passing underneath an Existing Subway Station as an example, the impact of different underpass construction methods on the Project is explored by numerical simulation. As shown in the analysis results, the multi-pilot hole step method has the least impact on the existing station, which can effectively control the progress of vault settlement and surface settlement deformation. The construction would result in large settlement deformation at the center of the existing station, and the closer distance from the central axis of the newly-built tunnel would create a greater settlement value, with the bottom settlement reaching 2.36mm during the excavation of the pilot holes. In the process of excavation, the surface settlement curve changes from the shape “M” to “V”, and the surface settlement due to the removal of temporary support accounts for 66% of the total settlement.