Effects Of Critical Factors Research Articles

Performance and economic analysis of a molten salt furnace thermal energy storage and peaking system coupled with thermal power units for iron and steel gas waste heat recovery

A new peaking system utilizing a molten salt furnace energy storage system coupled with a blast furnace gas thermal power unit in a steel mill is proposed, which stores excess blast furnace gas thermal energy in molten salt and releases the thermal energy for power generation during peak power demand. The heating efficiency of 74.57% is experimentally verified by building a molten salt furnace, and a 135 MW blast furnace gas thermal power unit is simulated using modeling to explore the energy storage and peak shifting performance and economic feasibility of the system. The results show that during the charging phase, the system can recover up to 9.361 t/h of standard coal, increasing the low valley regulation ratio to 20.31% with the increase of extraction rate. During the discharging phase, the system can provide an additional 17.42 MW of generating power, with a peak modulation ratio of 12.90%. The exergy losses from the combustion process dominates the overall system exergy losses with a maximum of 21.00 MW, followed by the exergy from the turbine, which occupies 18.42% of the input energy. The cycle efficiency of the system is up to 63.54%, and the molten salt temperature has a more significant impact on the system performance than the molten salt flow rate. The economic feasibility analysis yields a peaking capacity cost of $74.28/kWh for the modified system. The system will complete 100% recovery of the investment cost in 4.90 years, and thereafter, the annual profit is more than $3.71 Million. The peaking hours and regional electricity price are the main factors affecting the system. The effect of critical factors on the payback years of the system was further explored, and the payback years remains within 8 years only when the molten salt temperature is above 500 °C and the molten salt flow rate exceeds 400 t/h.

Research on the BIM Application Mechanism of Engineering-Procurement-Construction Projects Based on a Tripartite Evolutionary Game

This study establishes a tripartite evolutionary game model based on the assumptions of bounded rationality and the interaction behavior of governments, owners, and general contractors to examine how strategies are changing for three stakeholders regarding the building information modeling (BIM) application in engineering-procurement-construction (EPC) projects. The theoretical model was validated and the effects of critical factors on stakeholder decision making were discussed using case study and numerical simulation analysis. The results show that (1) the choice of the BIM application strategy in EPC projects is affected by the interactive behavior of participants in the game, (2) the reasonable subsidies contribute to the evolution of the ideal stable strategy, (3) the owners’ high standard of incentives for general contractors can accelerate BIM promotion, (4) the general contractors are more sensitive to the loss that may be caused by problems with the BIM application, and (5) the positive externalities generated by the application of BIM have a great impact on the wide application of BIM. And some suggestions are put forward toward improving the development of BIM in EPC projects on the basis of findings. This study may contribute to our current understanding of the interactions of stakeholders in EPC projects, as well as provide valuable management implications for the governments in order to promote the development of BIM.

Experimental and numerical investigations on the similitude effect of scaled lead rubber bearings for shaking table test

Small scaled lead rubber bearings (SLRBs) are widely used for shaking table tests in isolated tall buildings. Notably, research on the similitude effect of such bearings has rarely been conducted at the component and overall structural levels. Thus, two types of SLRBs with a diameter of 95 mm were designed according to the post-yield stiffness (i.e., SLRB95-A) and equivalent stiffness (i.e., SLRB95-B) to evaluate the existing design principle for the SLRB in the shaking table tests. At the component level, the mechanical characteristics of the two types of SLRBs were evaluated through vertical compression tests and compression-shear tests, and the effects of critical factors on the mechanical parameters were identified. A more desirable and stable performance was realized for SLRB95-B than for SLRB95-A. At the overall structural level, the seismic performance of the prototype structure and scaled structure using the two types of SLRBs were compared. A better agreement was observed between the distributions of the maximum inter-story drift ratio of the prototype structure and scaled structure using SLRB95-B compared to SLRB95-A. Based on these results, the SLRB is recommended to be designed based on the equivalent stiffness. The research outcome will provide a useful reference for the design of scaled lead rubber bearings for shaking table tests.

Aviation communication: the effect of critical factors on the rate of misunderstandings

PurposeIneffective communication consequences can be life-threatening and drastic. Communication misunderstandings are frequently reported in incidents, accidents and occurrences. This research paper aims to evaluate operator communication load in highly automated systems; distinguish and highlight the communication error factors during flight operations from different perspectives; and provide suggestions to operators to decrease the rate of misunderstandings in aviation communication.Design/methodology/approachThis study is based on a questionnaire that investigated the critical communication load, including aviation training, standard phraseology, operators’ native language and cultural background. In addition to the effect of using controller–pilot data link communications will be discussed widely. In this research, 110 responses were obtained from pilots and air traffic controller (ATCOs) that vary in 44 countries; approximately 20% were ATCOs, and 75% were pilots.FindingsThis study was designed to assess the level of aviation operators communication load in highly automated systems, identify and illustrate the factors that contribute to communication errors during flight operations from multiple viewpoints, and offer recommendations to operators to minimize the rate of misunderstandings in aviation communication.Originality/valueThis research deals with evaluating the operators’ communication load, which is crucial for the air traffic safety and efficiency.

Competition between cooling contraction and fluid overpressure on aperture evolution in a geothermal system

Comprehensive understanding of aperture evolution of HDR (hot dry rock) fracture is critical for enhancing permeability in a geothermal system. Coupled HM (hydro-mechanical) and THM (thermo-hydro-mechanical) simulations are conducted to elucidate the competition between cooling contraction and fluid overpressure in fracture aperture enhancement during heat extraction. The effects of critical factors, including fracture geometry, reservoir properties, and injection settings on this competitive relationship, are systematically examined. We find that (1) fracture aperture is dominated by the competing effect of cooling contraction and fluid overpressure; the cooling-induced aperture grows as the injection time increases, declining the overpressure-induced aperture; (2) high thermal expansion coefficient and low fracture normal stiffness tremendously enlarge total and cooling-induced apertures and mildly shrink the overpressure-induced aperture; (3) decreasing fracture spacing and increasing fracture length remarkably improves the total aperture; the former increases the cooling-induced aperture while the latter enhances the overpressure-induced aperture; (4) the reduction of injection temperature increases the cooling-induced aperture and lowers the overpressure-induced aperture; the growth of flow rate expands both the cooling-induced and overpressure-induced apertures. We thus unveiled the mystery of the invisible aperture evolution during heat extraction. The findings largely benefit the optimization of mining parameters of a geothermal reservoir.

The Crystallization Behavior and Stability of Chromite Synthesized in Chromium-Containing Wastewater at Room Temperature

The ferrite process can not only purify wastewater containing heavy metal ions but also recycle valuable metals from wastewater. Therefore, it is considered a promising technology to treat chromium-containing wastewater. However, the process has not been extensively applied in industry due to its high synthesis temperature. In this paper, the feasibility of chromite synthesis at room temperature was comprehensively studied. The effects of critical factors on the effluent quality and the crystallization behavior and stability of the synthetic products were investigated. Results showed that the removal ratio of chromium from wastewater was over 99.0%, and the chromium concentration in the supernatant reached the sewage discharge standard after undergoing the ferrite process at room temperature. Increases in the aeration rate, stirring rate, and reaction time were favorable for the formation of stable chromite. The particles obtained by the ferrite process at room temperature were characterized by a compact structure, and the maximum size of the particles reached 52 μm. Chromium gradually entered the spinel crystal structure during the synthesis process, and the molecular formula of the synthetic chromite might be Fe 3 − x Cr x O 4 , in which x was approximately 0.30. The path of the microscopic reaction was proposed to illuminate the synthesis mechanism of chromite under room temperature conditions. The present study has laid the foundation for the industrial application of the ferrite process in the purification and utilization of chromium-containing wastewater.

Attrition of high ash Ekibastuz coal in a bench scale fluidized bed rig under O2/N2 and O2/CO2 environments

While fluidized bed coal combustion technology has advanced significantly, attrition and its impact on combustion remains a problem. Using a bench scale fluidized bed unit, we examined the experimental attrition data for batches of coal ash particles. Experiments were carried out in the presence of bed material (sand) by adding coal particle to the hot riser, which has a height of 500 mm and internal diameter of 25.4 mm. Combustion of coal particles with high ash content was carried out in both O2/N2 and O2/CO2 environments. Coal particles with sizes of 0.4–0.8 mm and 0.8–1.4 mm were prepared by sieving and examined in this work. Using this data, the effect of critical factors on attrition such as gas velocity, particle size, and combustion environments were analyzed. In addition, the composition of ash particles was analyzed by SEM/EDX and XRF. The sizes of ash particles were less than 0.2 mm after combustion. A higher attrition rate was determined at higher gas velocity, regardless of the combustion environment. The ash composition analysis showed high concentration of silicon and aluminum oxide in the ash, and this possibly was increased due to kaolinite decomposition.

Simplified analytical solution for circular tunnel under obliquely incident SV wave

A simplified analytical solution is developed for estimating the thrusts and bending moments of the circular tunnel in half space under the obliquely incident SV wave. The seismic waves impinging on the tunnel is obtained according to the elastic wave motion theory in half space firstly, which is the superposition of the incident and reflected SV waves and reflected P wave. Then, by considering the tunnel lining as a thick-wall cylinder, analytical solutions for internal forces of circular tunnel due to the incident and reflected SV waves and the reflected P wave are deduced, which enables more precise forecasts than previous analytical solutions by the thin shell model. The total tunnel internal forces are obtained finally through the superposition of the above solutions under three kinds of waves. The accuracy of the proposed analytical solution is verified by comparing with the dynamic numerical results. Moreover, the discussion about the effect of critical factors on the accuracy of the proposed analytical solutions is conducted, including the tunnel structure inertia, the seismic wavelength, the lining thickness and the tunnel depth. These results demonstrate that the proposed analytical solution performs well and can be adopted to predict the internal forces of circular tunnel under obliquely incident SV wave in seismic design.

Thermal contact conductance between balls and bearing rings

The thermal contact conductance (TCC) between balls and bearing rings is predicted by proposing the TCC model between the curved and spherical surfaces. The Weierstrass-Mandelbrot function is applied to characterize the microscopic topography of surfaces. The fractal contact model is constructed by considering the elastic, elastic-plastic, and plastic deformations of microprotrusions, and then an effective contact coefficient is built to modify the fractal contact parameters. Finally, the TCC modeling method is proposed by considering the elastic and plastic TCCs of different contacting microprotrusions with different sizes. The experiments of TCCs were conducted under different conditions to verify the validity of the proposed model. The results show that the predicted TCCs fit well with measured values and that the predictive accuracy can be improved greatly by considering the effective contact coefficient. Then the effect of critical factors on TCCs is discussed, and the TCC increases with the external load, and increases with the fractal dimension D and decreases with the scaling constant G. The TCC of the dynamic lubricated ball bearing is much greater than that of the static lubricated ball bearing and the TCC of the static lubricated ball bearing is much greater than that of the static non-lubricated ball bearing.

Systematic vs. stepwise parameter optimization for discriminant model development: A case study of differentiating Pinellia ternata from Pinellia pedatisecta with near infrared spectroscopy

Near infrared (NIR) spectroscopy is an effective technique for adulteration detection in traditional Chinese medicine. The aim is to develop a discriminant model with the aid of chemometrics tools. The discriminant model is conventionally established by the means of stepwise optimization. This approach is often limited to trial-and-error and considered as a burden. In this study, a systematic optimization approach was proposed to develop the discriminant model with the aid of the design of experiment tools and applied to a case study of differentiating Pinellia ternata from Pinellia pedatisecta and adulterated Pinellia ternata using NIR spectroscopy. Spectral pretreatment, variable selection, and discriminant methods were identified as critical factors. The classification accuracy and no-error rate of the calibration set, cross-validation, and the prediction set were calculated to evaluate the performance of discriminant models. A full factorial design was applied to analyze the effect of critical factors at different levels on the model performance and optimize these factors. Three discriminant models including discriminant analysis coupled with principal component analysis (PCA-DA), partial least squares – discriminant analysis (PLS-DA), and k-nearest neighbors (KNN) were obtained by systematic optimization. The performance of PCA-DA and PLS-DA models obtained by systematic optimization was very good, and no samples were misclassified, which were better than those obtained by stepwise optimization. The performance of the KNN model obtained by systematic optimization was not desired and it was equal to that obtained by stepwise optimization. The results showed that Pinellia ternata could be successfully discriminated from Pinellia pedatisecta and adulterated Pinellia ternata by the PCA-DA and PLS-DA models. Compared to the stepwise optimization approach, the systematic optimization approach can improve the PCA-DA and PLS-DA model performance for differentiating Pinellia ternata from Pinellia pedatisecta and adulterated Pinellia ternata.

Insights into Electroreductive Dehalogenation Mechanisms of Chlorinated Environmental Pollutants

AbstractThe electroreductive cleavage of carbon‐chloro bonds has attracted increasing attention from both environmental and mechanistic points of view over the past decades, taking into consideration a large variety of chlorinated organic compounds. Important discoveries have been made on the underlying electron/hydrogen transfer mechanisms and the enhancement of dechlorination performance for electrocatalysis purposes over the last years. However, there is still missing a combined knowledge from individual researches to specially elucidate the electroreductive dehalogenation mechanisms of organic chlorides. Herein, we summarize the diverse electrochemical strategies applied to reductive dehalogenation of chlorinated environmental pollutants, including direct electrochemical reduction, electrocatalytic hydro‐dechlorination and electrochemically mediated reduction methods, and, especially, highlight the differences in reductive dehalogenation mechanisms. Specifically, direct electron transfer is the most common dechlorination mechanism involved in the direct electrochemical reduction of organic chlorides, in which the electron transfer to C−Cl bonds can be classified as concerted or stepwise dissociative electron transfer mechanism. Indirect atomic hydrogen reduction is the primary dechlorination mechanism in the electrocatalytic hydro‐dechlorination process, which often competes with the direct electrochemical reduction route. Electrochemically mediated reduction, as another indirect route, uses a redox‐active mediator to indirectly transfer electrons from cathode to organic chlorides, resulting in reductive dehalogenation reaction. Moreover, the effects of critical factors on the dehalogenation reactivity and mechanisms are also discussed to better demonstrate the electroreductive dehalogenation of organic chlorides. Lastly, this contribution highlights recent relevant advances in electroreductive dehalogenation issues, as well as the challenges and potentials of this process.

Effects of Solid Acid Supports on the Bifunctional Catalysis of Levulinic Acid to γ-Valerolactone: Catalytic Activity and Stability.

Heterogeneous transformation of levulinic acid (LA) to γ-valerolactone (GVL) is regarded as a critical process of the lignocellulose-based biorefinery system. Substantial progress on the catalytic conversion of LA to GVL has been continuously achieved recently. However, the traditional research paradigm typically emphasizes the metal-catalyzed hydrogenation step, but lacks profound insights into the potential impacts of catalyst supports. Herein, an overview of the bifunctional catalytic system classified by representative solid acid supports for LA conversion to GVL is presented, and effects of critical factors on metal- and acid- catalyzed processes are discussed. Particularly, impacts of key issues on catalytic stability are thoroughly summarized and analyzed. Challenges and suggestions are also proposed from the perspective of increases in both catalytic activity and stability. This review potentially contributes to the rational design of high-efficiency catalysts used in the biomass valorization for renewable energy production.

Assessing the Impact of Formulation Variables on Dissolution Profile of Sustained Release Tablet of Metformin Hydrochloride by Quality by Design Approach

In the present study, sustained release tablet of metformin hydrochloride were formulated and analyse the impact of material and process attributes on dissolution profile employing Quality by design (QbD) approach. Taguchi design was employed to screen the critical factors and amount of HPMC, amount of compritol and compression force was selected as critical factors. The effect of critical factors on the critical quality attributes (CQAs) of sustained, such as cumulative drug release at 2 hr (CDR 2), at 5 hr (CDR 5) and 8 hr (CDR8) was evaluated using Box-Behnken design. The optimised formulation was achieved with set of variable, such as a amount of HPMC (24.9%), amount of compritol (6.93%) and compression force (7.09 KN) and resulted into a tablet with a cumulative drug release 18.53%, 47.10% and 85% at 2, 5 and 8 hr respectively which was close to predicted value.

Effects of Travel Time Reliability and Commodity Characteristics on Hinterland Leg Transportation of Export Containers

Increasing the mode share of railway in hinterland leg containers transportation requires a better understanding about the effects of critical factors on shippers’ mode choices. This paper focuses on the effects of travel time reliability (TTR) and commodity characteristics on freight mode choice. A two-stage survey is conducted in the Yiwu-Port of Ningbo corridor, China, to collect shippers’ preference data. Five model specifications are estimated using these data. Estimation results of generic parameters indicate that significant interaction effects between commodity characteristics and travel time exist. The value of generic reliability was then calculated and the effects of commodity characteristics was quantified. In addition, mode-specific values of reliability are estimated. Remarkable differences are found in the mode-specific value of reliability for different modes. Also, the effects of mode-specific value of reliability on the demand forecasting were investigated. Results imply that the mode share of railway will be underestimated if the mode-specific value of reliability is neglected, especially when travel time of railway transportation is reliable. Therefore, it is recommended that the mode-specific willingness-to-pay should be considered in railway demand forecasting and project appraisals.

Evaluation and identification of factors affecting the growth of real estate market in India

The purpose of this article was to evaluate and identify the various factors and also know the effect of critical factors on the growth of the real estate market in India. we have applied the exploratory research design to know the new facts about the real estate market and formulate the null hypothesis and also used the descriptive research design to test the null hypothesis on the basis of using the regression analysis. After analyzing the above case we would be in a position to know the effect of the various critical factors on the growth of the real estate market in India. The sample size for this study was 260. The practical implication of this research paper was to know the real estate market growth in India.Since this research was conducted purely on the basis of the primary data, hence we are sure for the originality of this research paper.

Evaluation and identification of factors affecting the growth of real estate market in India

The purpose of this article was to evaluate and identify the various factors and also know the effect of critical factors on the growth of the real estate market in India. we have applied the exploratory research design to know the new facts about the real estate market and formulate the null hypothesis and also used the descriptive research design to test the null hypothesis on the basis of using the regression analysis. After analyzing the above case we would be in a position to know the effect of the various critical factors on the growth of the real estate market in India. The sample size for this study was 260. The practical implication of this research paper was to know the real estate market growth in India.Since this research was conducted purely on the basis of the primary data, hence we are sure for the originality of this research paper.

Evaluation of a membrane permeation system for biogas upgrading using model and real gaseous mixtures: The effect of operating conditions on separation behaviour, methane recovery and process stability

Abstract In this paper, the enrichment of methane by membrane technology was studied by employing (i) a model as well as (ii) a real biogas mixture produced on a laboratory-scale. Thereafter, the endurance of the process was tested at an existing biogas plant. The commercial gas separation module under investigation contained hollow fiber membranes with a polyimide selective layer. During the measurements, the effect of critical factors (including the permeate-to-feed pressure ratio and the splitting factor) was sought in terms of the (i) CH4 content on the retentate-side and (ii) CH4 recovery, which are important measures of biogas upgrading efficiency. The results indicated that a retentate with 93.8 vol% of CH4 – almost biomethane (>95 vol% of CH4) quality – could be obtained using the model gas (consisting of 80 vol% of CH4 and 20 vol% of CO2) along with 77.4% CH4 recovery in the single-stage permeation system. However, in the case of the real biogas mixture, ascribed primarily to inappropriate N2/CH4 separation, the peak methane concentration noted was only 80.7 vol% with a corresponding 76% CH4 recovery. Besides, longer-term experiments revealed the adequate time-stability of membrane purification, suggesting such a process is feasible under industrial conditions for the improvement of biogas quality.

A quantitative analysis on the effects of critical factors limiting the effectiveness of species conservation in future time.

The effectiveness of conservation plans depends on environmental, ecological, and socioeconomic factors. Global change makes conservation decisions even more challenging. Among others, the components of most concern in modern‐day conservation assessments are as follows: the magnitude of climate and land‐use changes; species dispersal abilities; competition with harmful socioeconomic activities for land use; the number of threatened species to consider; and, relatedly, the available budget to act. Here, we provide a unified framework that quantifies the relative effects of those factors on conservation. We conducted an area‐scheduling work plan in order to identify sets of areas along time in which the persistence expectancies of species are optimized. The approach was illustrated using data of potential distribution of ten nonvolant mammal species in Iberia Peninsula from current time up to 2080. Analyses were conducted considering possible setups among the factors that are likely to critically impact conservation success: three climate/land‐use scenarios; four species’ dispersal kernel curves; six land‐use layer types; and two planning designs, in which assessments were made independently for each species, or joining all species in a single plan. We identified areas for an array of investments levels capable to circumvent the spatial conflicts with socioeconomic activities. The effect of each factor on the estimated species persistence scores was assessed using linear mixed models. Our results evidence that conservation success is highly reliant on the resources available to abate land‐use conflicts. Nonetheless, under the same investment levels, planning design and climate change were the factors that most shaped species persistence scores. The persistence of five species was especially affected by the sole effect of planning design and consequently, larger conservation investments may retard climatic debts. For three species, the negative effects of a changing climate and of multiple‐species planning designs added up, making these species especially at risk. Integrated assessments of the factors most likely to limit species persistence are pivotal to achieve effectiveness.

ELECTROCHEMICAL DEGRADATION OF CLINDAMYCIN BY ANODIC OXIDATION ON SnO2-Sb COATED TITANIUM ANODES

Degradation of Clindamycin phosphate (CMP) was studied in aqueous solutions by an anodic oxidation process under galvanostatic conditions. The electrolysis cell consisted of a Ti/SnO2-Sb anode, prepared by dip-coating technique, and a 316 stainless steel cathode, both of which had a surface area of 6 cm2. The effects of critical factors, including CMP concentration, current density, initial pH, and the supporting electrolyte were evaluated. The electrochemical oxidation of CMP was controlled by mass transport within the studied range. The kinetic analysis indicated that the degradation reactions followed pseudo-first-order equation. The rate of CMP decay, as well as that of COD removal, decreased with increasing initial concentrations. Better Instantaneous Current Efficiency (ICE) values were obtained at higher organic concentrations, due mainly to the increased mass transfer flux towards non-active anode surface. Increasing current density and initial pH led to the faster removal of CMP, primarily because of enhanced electrogenerated hydroxyl radicals (�OH) on the anode surface. However, COD reduction was found to be pH independent. The removal rates of CMP and COD were also discussed with respect to the supporting electrolyte in different types and concentrations. The GC-MS analysis indicated that tert-butyl compounds were the major organic intermediates for the electrochemical degradation of Clindamycin. © 2018, Gheorghe Asachi Technical University of Iasi, Romania. All rights reserved.

Critical Components for Maintenance Outage Scheduling Considering Weather Conditions and Common Mode Outages in Reconfigurable Distribution Systems

This paper proposes a model for identifying critical components that affect the maintenance outage scheduling in reconfigurable distribution systems. The model considers critical factors such as prevailing severe weather conditions and component aging conditions, common mode outages, and repair rates in distribution systems. The effects of critical factors on forced outage rates of distribution system components are quantified by the proportional hazard model. A recursive sampling method is proposed to generate Monte Carlo scenarios with the given forced outage rate. In each scenario, the distribution system reconfiguration is optimized efficiently using a standard mixed-integer second-order cone program. Then absolute and relative criticality indices are calculated to describe the criticality of components. A new scenario is generated subsequently and the process is continued in the following iteration until the convergence condition is satisfied. The overall convergence of multiple scenarios is quantified by the coefficient of variation of criticality index. The final absolute and relative criticality indices are the average over multiple scenarios. The influence of component aging condition and forced outage characteristics, weather condition, and the system reconfiguration on component criticality for the maintenance outage scheduling is distinguished and exhibited in case studies. The case studies illustrate the effectiveness of proposed model and the solution method for identifying the critical components.