Robust Optimization Method of Cylindrical Roller Bearing by Maximizing Dynamic Capacity Using Evolutionary Algorithms

Optimization of cylindrical roller bearings(CRBs)has been performed using a robust design.It ensures that the changes in the objective function,even in the case of variations in design variables during manufacturing,have a minimum possible value and do not exceed the upper limit of a desired range of percentage variation.Also,it checks the feasibility of design outcome in presence of manufacturing tolerances in design variables.For any rolling element bearing,a long life indicates a satisfactory performance.In the present study,the dynamic load carrying capacity C,which relates to fatigue life,has been optimized using the robust design.In roller bearings,boundary dimensions(i.e.,bearing outer diameter,bore diameter and width)are standard.Hence,the performance is mainly affected by the internal dimensions and not the bearing boundary dimensions mentioned formerly.In spite of this,besides internal dimensions and their tolerances,the tolerances in boundary dimensions have also been taken into consideration for the robust optimization.The problem has been solved with the elitist non-dominating sorting genetic algorithm(NSGA-II).Finally,for the visualization and to ensure manufacturability of CRB using obtained values,radial dimensions drawing of one of the optimized CRB has been made.To check the robustness of obtained design after optimization,a sensitivity analysis has also been carried out to find out how much the variation in the objective function will be in case of variation in optimized value of design variables.Optimized bearings have been found to have improved life as compared with standard ones.

Effect of dynamic loading conditions on the dynamic performance of MP1 energy-absorbing rockbolts:Insight from laboratory drop test

Energy-absorbing rockbolts have been widely adopted in burst-prone excavation support, and their serviceability is closely related to the frequency and magnitude of seismic events. In this research, the splittube drop test with varying impact energy was conducted to reproduce the dynamic performance of MP1rockbolts under a wide range of seismic event magnitudes. The test results showed that the impact process could be subdivided into four distinct stages, i.e. mobilization, strain hardening, plastic flow(ductile), and rebound stage, of which strain hardening and plastic flow are the primary energy absorbing stages. As the impact energy per drop increases from 8.1 to 46.7 k J, the strain rate of the shank varies between 1.20 and 2.70 s^(-1), and the average impact load is between 240 and 270kN, which may be considered as constant. The MP1 rockbolt has a cumulative maximum energy absorption(CMEA) of 31.9–40.0 k J/m, with an average of 35.0 k J/m, and the elongation rate is 11.4%–14.7%, with an average of 12.7%, both of which are negatively correlated with the impact energy per drop. Regression analysis shows that energy absorption and shank elongation, as well as momentum input and impact duration,conform to the linear relationship. The complete dynamic capacity envelope of MP1 rockbolts is proposed, which reflects the dynamic bearing capacity, elongation, and distinct stages. This study is helpful to better understand the dynamic characteristics of energy-absorbing rockbolts and assist design engineers in robust reinforcement systems design to mitigate rockburst damage in seismically active underground excavations.

Efficient acetylene/carbon dioxide separation with excellent dynamic capacity and low regeneration energy by anion-pillared hybrid materials

Adsorptive separation of acetylene/carbon dioxide mixtures by porous materials is an important and challenging task due to their similar sizes and physical properties.Here,remarkable acetylene/carbon dioxide separation featuring a high dynamic breakthrough capacity for acetylene(4.3 mmol·g^(–1))as well as an ultralow acetylene regeneration energy(29.5 kJ·mol^(–1))was achieved with the novel TiF_(6)^(2–)-pillared material ZU-100(TIFSIX-bpy-Ni).Construction of a pore structure with abundant TiF_(6)^(2–)anion sites and pores with appropriate sizes enabled formation of acetylene clusters through hydrogen bonds and intermolecular interactions,which afforded a high acetylene capacity(8.3 mmol·g^(–1))and high acetylene/carbon dioxide uptake ratio(1.9)at 298 K and 1 bar.Moreover,the NbO_(5)^(2–)anion-pillared material ZU-61 investigated for separation of acetylene/carbon dioxide.In addition,breakthrough experiments were also conducted to further confirm the excellent dynamic acetylene/carbon dioxide separation performance of ZU-100.

Optimal Design of Tapered Roller Bearings Based on Multi⁃Physics Objectives Using Evolutionary Algorithms

Rolling element bearing is the most common machine element in rotating machinery.An extended life is among the foremost imperative standards in the optimal design of rolling element bearings,which confide on the fatigue failure,wear,and thermal conditions of bearings.To fill the gap,in the current work,all three objectives of a tapered roller bearing have been innovatively considered respectively,which are the dynamic capacity,elasto-hydrodynamic lubrication(EHL)minimum film⁃thickness,and maximum bearing temperature.These objective function formulations are presented,associated design variables are identified,and constraints are discussed.To solve complex non⁃linear constrained optimization formulations,a best⁃practice design procedure was investigated using the Artificial Bee Colony(ABC)algorithms.A sensitivity analysis of several geometric design variables was conducted to observe the difference in all three objectives.An excellent enhancement was found in the bearing designs that have been optimized as compared with bearing standards and previously published works.The present study will definitely add to the present experience based design followed in bearing industries to save time and obtain assessment of bearing performance before manufacturing.To verify the improvement,an experimental investigation is worthwhile conducting.

Obstacles to the Success of Organizational and Managerial Innovation in Construction SMEs in Burkina Faso

This research is based on a qualitative approach based on the exploitation of secondary data.The objective of the research is to determine the factors likely to influence the success of innovation in small and medium enterprises(SMEs)of Building and Public Works(BTP)in Burkina Faso.To do this,we issued two research proposals that served as a guide for our research.It emerged that 77% of SMEs reported having innovated in 2019,while the same study concluded to the underperformance of these companies.Hence,there is the need to distinguish between innovation actions and the success of innovation.For us,the success of innovation is based on information transparency in the company and the development of human resources.The results showed that the information does not circulate the construction companies and it results in a lack of meeting place.In addition,construction and civil engineering SMEs lack competent and qualified staff and are not very motivated.Indeed,only 52% of business leaders are satisfied with the motivation of their staff.In terms of competence,97% business leaders say that they have qualified staff and even 87% say not to delegate because they lack qualified staff.In fact,obtaining approval requires the existence of qualified personnel in the company,which justifies this assertion to 97%.And yet,the staff presented for the approval is not the one available in the company.Moreover,the lack of competent and motivated staff is confirmed by the MOE and MOD.Our two research proposals have been validated.However,we noted that this is a partial search for the factors that influence the success of innovation in construction SMEs that could be complemented by other research.

Change of stream network connectivity and its impact on flood control

AbstUrbanization can alter the hydrogeomorphology of streams and rivers,change stream network structures,and reduce stream network connectivity,which leads to a decrease in the storage capacity of stream networks and aggravates flood damage.Therefore,investigation of the ways in which stream network connectivity impacts flood storage capacity and flood control in urbanized watersheds can provide significant benefits.This study developed a framework to assess stream network connectivity and its impact on flood control.First,a few connectivity indices were adopted to assess longitudinal stream network connectivity.Afterward,the static and dynamic storage capacities of stream networks were evaluated using storage capacity indices and a one-dimensional hydrodynamic model.Finally,the impact of stream network connectivity change on flood control was assessed by investigating the changes in stream network connectivity and storage capacity.This framework was applied to the Qinhuai River Basin,China,where intensive urbanization has occurred in the last few decades.The results show that stream network storage capacity is affected by stream network connectivity.Increasing stream network connectivity enhances stream network storage capacity.©2020 Hohai University.Production and hosting by Elsevier B.V.This is an open access article under the CC BY-NC-ND license(http://creativecommons.org/licenses/by-nc-nd/4.0/).

Effect of cobalt doping on ceria-zirconia mixed oxide: Structural characteristics, oxygen storage/release capacity and three-way catalytic performance

The effect of Co doping on ceria-zirconia mixed oxides was investigated for Co0.1Ce0.6Zr0.3Ox sample prepared by sol-gel method. The Pd-only three-way catalyst （TWC） was obtained by incipient wetness impregnation with 0.5 wt.% Pd loading. The structural and oxygen handling properties were analyzed by X-ray diffraction （XRD）, H2-temperature programmed reduction （H2-TPR） and the dynamic oxygen storage capacity （DOSC）. The introduction of Co into ceria-zirconia lattice strongly modified the mobility of oxygen and enhanced the DOSC performance. Pd-only TWC based on the Co0.1Ce0.6Zr0.3Ox support exhibited superior activity for water-gas shift and steam reforming and ampli- fied amplitude of stoichiometric window.

Dynamic statistical information theory

In recent years we extended Shannon static statistical information theory to dynamic processes and established a Shannon dynamic statistical information theory, whose core is the evolution law of dynamic entropy and dynamic information. We also proposed a corresponding Boltzmman dynamic statistical information theory. Based on the fact that the state variable evolution equation of respective dynamic systems, i.e. Fok- ker-Planck equation and Liouville diffusion equation can be regarded as their information symbol evolution equation, we derived the nonlinear evolution equations of Shannon dy- namic entropy density and dynamic information density and the nonlinear evolution equa- tions of Boltzmann dynamic entropy density and dynamic information density, that de- scribe respectively the evolution law of dynamic entropy and dynamic information. The evolution equations of these two kinds of dynamic entropies and dynamic informations show in unison that the time rate of change of dynamic entropy densities is caused by their drift, diffusion and production in state variable space inside the systems and coordinate space in the transmission processes; and that the time rate of change of dynamic infor- mation densities originates from their drift, diffusion and dissipation in state variable space inside the systems and coordinate space in the transmission processes. Entropy and in- formation have been combined with the state and its law of motion of the systems. Fur- thermore we presented the formulas of two kinds of entropy production rates and infor- mation dissipation rates, the expressions of two kinds of drift information flows and diffu- sion information flows. We proved that two kinds of information dissipation rates (or the decrease rates of the total information) were equal to their corresponding entropy produc- tion rates (or the increase rates of the total entropy) in the same dynamic system. We obtained the formulas of two kinds of dynamic mutual informations and dynamic channel capacities reflecting the dynamic dissipation characteristics in the transmission processes, which change into their maximum—the present static mutual information and static channel capacity under the limit case where the proportion of channel length to informa- tion transmission rate approaches to zero. All these unified and rigorous theoretical for- mulas and results are derived from the evolution equations of dynamic information and dynamic entropy without adding any extra assumption. In this review, we give an overview on the above main ideas, methods and results, and discuss the similarity and difference between two kinds of dynamic statistical information theories.

Recent advances in zinc-ion hybrid energy storage: Coloring high-power capacitors with battery-level energy

Zinc-ion hybrid capacitors(ZICs) are considered as newly-emerging and competitive candidates for energy storage devices due to the integration of characteristic capacitor-level power and complementary battery-level energy. The practical application of rising ZICs still faces the specific capacity and dynamics mismatch between the two electrodes with different energy storage mechanisms, which cannot meet the ever-growing indicator demand for portable electronic displays and public traffic facilities. Focusing on these unresolved issues, this mini-review presents recent advances in ZICs referring to the hybrid energy storage mechanism, design strategies of both capacitor-type and battery-type electrode materials, and electrolyte research toward advanced performances(e.g., high operational potential, wide adaptive temperature). Finally, current challenges and future outlook have been proposed to guide further exploration of next-generation ZICs with a combination of high-power delivery, high-energy output and high-quality service durability.

Construction of bimetallic Pt-Pd/CeO_(2)-ZrO_(2)-La_(2)O_(3) catalysts with different Pt/Pd ratios and its structure-activity correlations for three-way catalytic performance

A series of Pt-Pd bimetallic catalysts supported on CeO_(2)-ZrO_(2)-La_(2)O_(3) mixed oxides were synthesized through the conventional impregnation method.Three-way catalytic performance evaluations along with detailed physio-chemical characterizations were carried out to establish possible structure-activity correlations.Results show that on the one hand,different Pt/Pd ratios can strongly affect the TWC behaviors of Pt-Pd/CZL catalysts by modulating the synergistic effect between Pt and Pd.On the other hand,higher Pt/Pd ratio also favors better dispersion of precious metals.Such improved precious metals(PM)dispersion can promote the metal-support interaction and increase the surface oxygen vacancies concentration,thereby raising the dynamic oxygen storage/release capacity,improving the redox ability as well as enha ncing the thermal stability of the Pt-Pd/CZL catalyst.Moreover,the stro ng metal-support interaction can augment surface oxygen vacancy concentration,thereby benefiting low temperature CO and NO reaction via augmented NOxadsorption and nitrate conversion.

Preparation of Fe_x Ce_(1-x) O_y solid solution and its application in Pd-only three-way catalysts

FeOx-CeO2 mixed oxides with increasing Fe/（Ce＋Fe） atomic ratio （1-20 mol%） were prepared by sol-gel method and characterized by X-ray powder diffraction （XRD）, Brunauer-Emrnett-Teller （BET） and Hydrogen temperature-programmed reduction （H2-TPR） techniques. The dynamic oxygen storage capacity （DOSC） was investigated by mass spectrometry with CO/O2 transient pulses. The powder XRD data following Rietveld refinement revealed that the solubility limit of iron oxides in the CeO2 was 5 mol% based on Fe/（Ce＋Fe）. The lattice parameters experienced a decrease followed by an increase due to the influence of the maximum solubility limit of iron oxides in the CeO2. TPR analysis revealed that Fe introduction into ceria strongly modified the textual and structural properties, which influenced the oxygen handling properties. DOSC results revealed that Ce-based materials containing Fe oxides with multiple valences contribute to the majority of DOSC. The kinetic analysis indicated that the calculated apparent kinetic parameters obey the compensation effect. The three-way catalytic performance for Pd-only catalysts based on the Fe doping support exhibited the redundant iron species separated out of the CeO2 and interacted with the ceria and Pd species on the surface, which seriously influenced the catalytic properties, especially after hydrothermal aging treatment.

Protein adsorption in two-dimensional electrochromatography packed with superporous and microporous cellulose beads

Anion-exchange superporous cellulose(DEAE-SC)and microporous cellulose(DEAE-MC)adsorbents were packed in an electrochromatographic column,and the effect of external electric field(eEF)on the dynamic adsorption was investigated.The column was designed to provide longitudinal,transverse or 2-dimensional(2D)eEF.It was found that the electro-kinetic effect caused by the introduction of an electric field played an important role in the dynamic adsorption of bovine serum albumin to the adsorbents.The dynamic binding capacity(DBC)in the presence of 2D eEF was higher than in the presence of a one-dimensional eEF.The effect of flow velocity on the DBC of the two adsorbents was also demonstrated.It was found that the effect of electric field on the DEAE-MC column was more remarkable than that on the DEAE-SC column at the same flow rate,whereas the DEAE-SC column showed higher DBC and adsorption efficiency(AE)than the DEAE-MC column.With increasing flow rate,the DEAE-SC column could still offer high DBC and AE in the presence of the 2D eEF.For example,a DBC of 21.4mg/mL and an AE of 57.7%were obtained even at a flow rate as high as 900cm/h.The results indicate that the 2D electrochromatography packed with the superporous cellulose adsorbent is promising for high-speed protein chromatography.