Cycle Time Duration Research Articles

Heat storage in solar adsorption refrigeration systems: A case study for indigenous fruits preservation

The present study deals with heat storage in a solar-powered refrigeration system designed for indigenous products preservation in a cold room with a positive temperature. One of the key goals of this study is to show the importance of heat storage and the choice of the suitable coupling, position, and technology of thermal heat storage in these systems to ensure energy management and system operation flexibility. A new system configuration design where the direct connection between the solar collectors and the adsorption chiller used in the directly driven chiller without any heat storage module and in the classic storing system is suppressed and a new special regulation system is added to manage the temperature of the supplied water to the adsorption chiller. Under the same solar collectors' area, the new configuration design performs well than the existing configurations and offers more flexibility and stability to the system. It was found that, the heat storage, performed by a Hot Water Tank (HWT), enhances the system's cooling production time duration as well as offers stability and reduces the highly fluctuant hot water temperature in solar adsorption chillers. It's shown that the choice of the adsorption chiller cycle time duration is of great importance as well as the HWT volume on the system's performance. The study shows also that the system achieves better performances when considering a stratified HWT instead of a fully mixed HWT. Using a total solar collectors' area of 84.53 m2, a hot water tank of 3 m3, and a cycle time of 1200 s, a solar fraction of 86% is obtained when the proposed configuration is connected to the stratified heat storage technology however 80% is reached when the system is equipped with the mixed hot water tank.

A laboratory study on fracture initiation and propagation of granite under cyclic-injection hydraulic fracturing

The abundant geothermal energy in hot dry rock (HDR) geothermal reservoirs is an attractive renewable energy resource with great potential. Cyclic injection in hydraulic fracturing has been proved to be a suitable way for the geothermal energy exploitation. However, the fracture initiation and propagation regimes induced by cyclic injection have been inadequately studied, and the fracturing optimization for HDR is often by experience. For this reason, true tri-axial hydraulic-fracturing tests were conducted to study the initiation and propagation of hydraulic fractures, while the specimens were subjected to the cyclic injection with different cycle time duration and injection rate. The results revealed that the initiation of hydraulic fracture was displayed as three basic patterns, and these fracture-initiation patterns were developed into two fracture geometries: simple fracture with only 2–4 strands and complex fracture network with >4 strands. The main reason for this difference is that the initiation and propagation of hydraulic fracture is controlled by the way of fluid circulation, and the cycle time duration and injection rate each played a different role in hydraulic fracturing. At a low injection rate, the initiation and propagation of hydraulic fractures under the high-frequency cycle (cycle time duration = 10 and 20 s) are mainly controlled by the change of injection pressure. Here, the hydraulic energy mainly acts on the rock near the well. The frequent change of injection pressure promotes the initiation of micro-fractures and forms a complex but short hydraulic fracture network. However, when high injection rate is subjected, too high and too low cycle frequencies (cycle time duration = 5 and 40 s) both tend to form a simple fracture, but the fracture has strong extension ability. With that, the similarity criterion of physical phenomena between the on-site prototype and the experimental model were discussed, and these lab-scale results were translated into the fracturing site of HDR.

Development of a model for analyzing the impact of configuration integrity loss on the aircraft product cycle time duration

One of the most important criteria in the production of modern aircraft is the length of the production cycle (lead-time). This indicator largely determines the commercial product success. In the framework of this work, issues of ensuring electronic layout and configuration integrity at various life cycle stages of a modern aircraft. The problem started in one aircraft enterprise in case of impossibility to provide assembly ability of different parts. A serious problem is the designation of tolerances on the parts dimensions. A model for eliminating contradictions in deviations created. One of the most important research questions is the issue of reducing the duration of the production cycle through optimization and control of the electronic layout and product configuration. Using modern approaches for setting product dimensional chains, using electronic layout optimization - a list of recommendations for the product design process developed. A methodology compiled to save the integrity of the digital layout at the various aircraft design stages. Was created simulating model which describe all assembly stages. The influence of configuration integrity loss on the product cycle time was shown.

Evaluation of the Biomechanical Parameters of Human-Wheelchair Systems during Ramp Climbing with the Use of a Manual Wheelchair with Anti-Rollback Devices

Purpose: The main purpose of the research conducted was the analysis of kinematic and biomechanical parameters measured during manual wheelchair ramp-climbing with the use of the anti-rollback system and the comparison of the values tested with the manual wheelchair climbing the same ramp but without any modifications. The paper presents a quantitative assessment relating to the qualitative research of the anti-rollback system performed by another research team. Method and materials: The article presents the measurement results of the wheelchair motion kinematics and the activity of four upper limb muscles for eight subjects climbing a 4.58° ramp. Each subject propelled the wheelchair both with and without the anti-rollback system. The kinematic parameters were measured by means of two incremental encoders with the resolution of 500 impulses per single revolution of the measurement wheel. Whereas, the muscle activity was measured by means of surface electromyography with the use of Noraxon Mini DTS apparatus equipped with four measurement channels. Results: The surface electromyography measurement indicated an increase in the muscle activity for all four muscles, during the use of the anti-rollback system. The increase was: 18.56% for deltoid muscle anterior, 12.37% for deltoid muscle posteriori, 13.0% for triceps brachii, and 15.44% for extensor carpi radialis longus. As far as the kinematics analysis is concerned, a decrease in the measured kinematic parameters was observed in most participants. The medium velocity of the propelling cycle decreased by 26%. The ratio of the generated power and the loss power in a single propelling cycle λ had decreased by 18%. The least decrease was recorded for the measurement of mechanical energy E and the propelling cycle duration time. For the total mechanical energy, the decrease level was 3%, and for the propelling cycle duration it was 1%. The research carried out did not demonstrate any impact of the anti-rollback system use on the push phase share in the entire propelling cycle.

Investigation on the effect of Si addition to the high temperature cyclic oxidation behaviour of β-NiAlDy alloy used in advanced jet engine applications

Abstract This work concentrates on the study of the effect of addition of Si to the β-NiAlDy alloy in improving its cyclic oxidation behaviour at high temperature namely 1000 0C. Silicon addition of 1%, 3% and 5% are carried out to prepare β-NiAlDy alloy groups by arc-melting and further by casting in inert atmosphere. The prepared alloy groups were further subjected to annealing in vacuum at temperature namely 1100 0C for a time period of 12 h. These alloy groups are subjected to cyclic oxidation tests up to 100 cycles with each cycle time duration of 5 h of atmospheric exposure at aforementioned temperature. The oxidation behaviour of the alloy groups were studied in detail by carrying out cyclic oxidation measurements, XRD, SEM and EDAX analysis. The results clearly show the variation of oxidation behaviour of the β- NiAlDy alloy when Si content is increasing from 1 to 5%. It is registered that the oxidation resistance of β-NiAlDy increase to a greater extent when 1 to 5% Si is added to the alloy.

ОПРЕДЕЛЕНИЕ ПАРАМЕТРОВ ШНЕКОЛОПАСТНОГО СМЕСИТЕЛЯ

The purpose of the study is to improve the equipment for mixing dry crumbled feed with regard to the basic opera-tion condition or parameters. As a result of the issue analysis and the existing mixers structure, it was found that many machines used for the preparation of compound feeds are complex in the structure and not reliable in opera-tion, the feed mixture quality does not always meet the zootechnical requirements; the applied standard and exper-imental mixers of compound feeds because of imperfection of technological process and working parts contained, possess high specific power consumption. The construction of a universal low-speed batch mixer with a fixed rec-tangular case and combined two forcibly mixing working parts mounted horizontally is an advanced study direction for feed mixers improving. The study objectives incorporated the development of structural and technological speci-fication of a low-speed auger-blade mixer of batch action; the assessment of the impact of design parameters above mentioned of the mixer on its performance; to identify the rational structural and operating specification of the auger-blade mixer taking into consideration the cycle duration time. The research methodology provided the theo-retical justification of specification of the mixer taking into account the cycle duration period of the blending. Ex-pressions to determine the performance efficiency along the following stages were provided: involving auger con-veyor, the first and the second mixing transporting and throwing blades. Formulas are obtained for estimation the cycle period from the installation angle of the mixing-transporting blades and the rotation frequency of the working parts. Data obtained and given for estimation the cycle time from the installation angle of the mixing-transporting blades and the speed of the working parts allow to operate during the minimum cycle time, that is, to choose the op-timal angle of installation of the blades and the speed of rotation of the working parts.

Analysis on multiple optical line terminal passive optical network based open access network

Passive optical networks (PONs) offer sufficient bandwidth to transfer huge amount having different packet sizes and data rates being generated by fusion of various networks. Additionally, multiple optical line terminals (OLTs) PONs reduce the computational complexity of data processing for nonuniform traffic. However, in order to improve the bandwidth allocation efficiency of a mixture of service providers, dynamic bandwidth algorithm (DBA) is needed for uplink communication. In this paper, a PON based open access network (OAN) is analyzed for bi-directional communication at various data rates. Multiple wavelengths are used to modulate the data of various service providers to evade the complicated DBA for uplink data broadcasting. The performance of the network is reported in terms of bandwidth exploitation, uplink effectiveness, overhead-to-data ratio and time cycle duration. The network is analyzed at various data rates to reveal the data accommodation capacity.

DNA Composition and Mitotic Time Cycle Duration in the Evolution of Faba Bean and Its Wild Relatives

The composition of nuclear DNA and mitotic time cycle in Vicia faba, commonly known as Faba bean, and its close relatives grouped together in Narbonensis species complex are compared. The melting profile and buoyant density gradient analysis in the species, V. narbonensis, V. serratifolia, V. galilaea and V. hyaeniscyamus belonging to Narbonensis species complex and V. faba did not show any appreciable change in the base composition. The density gradient profiles in the species belonging to the complex showed the presence of a distinct satellite fraction in each species. This satellite fraction was absent in V. faba. The change in the total duration or the duration of different stages of mitotic cycle in the species belonging to the species complex was not significantly different. In comparison, V. faba had longer mitotic cycle duration.

Совершенствование сортиментной заготовки древесины

Perestroyka in Russia has made significant adjustments to the technology of timber harvesting. Despite a number of significant advantages of tree length technology of timber compared to CTL, at logging enterprises CTL timber is widely used. The reasons of moving for the assortment technology of logging are considered. Diagram of logging site using harvester is given. The description of technology of felling, limbing and bucking of obtained timber on assortments is presented. Shortcomings of the harvester on this technology are marked. A new way to design cutting areas (technology) is suggested. The description of the two-step sequence of harvester operations is given. The proposed method of site logging will avoid hanging tree felling, reduce damage to growing trees, which is especially important during the selective cutting, significantly reduce the load on the harvester head, on the arm elements (handle, arrow) and on the chassis of the harvester, reduce the total distance for dragging a tree trunk and a weight of dragging part during processing. Criteria indicators are shown, the value of which can be seen on the process and can give its qualitative assessment. Performance of the harvester is determined, which is one of the most important technological parameters of the machine. The principle of machines forming in the system is equal or multiples of their performance. Components of the cycle time to process a single tree on the proposed technology of harvester work are listed. Necessary conclusions were draw based on the analysis of cycle time duration for a tree processing, taking into account composition and sequence of elements of operations of harvester for known and proposed schemes.

A genetic algorithm approach for a single hoist scheduling problem with time windows constraints

This study considers a cyclic scheduling of hoist movements in electroplating industry. Several jobs have to flow through a production line according to an ordered bath sequence. They firstly enter the line at a loading buffer. Then they will be soaked sequentially in a series of tanks containing specific chemical baths. Finally, they will leave the line at the unloading buffer. The processing time duration of each job in each tank is not constant but confined within a time window bounded by a minimum and a maximum duration. If a job spends less than the minimum duration or more than the maximum duration it is considered defective. Moreover, not only the job operations in the soaking tanks have to be scheduled, but also the transportation of the jobs between tanks has to be considered. The problem now is to find an optimum or near optimum feasible cyclic scheduling such that the hard resource and time-window constraints are respected and the cycle time duration is minimized. A mathematical formulation is proposed for the multi-jobs cyclic hoist scheduling problem with a single transportation resource, and a Genetic Algorithm (GA) approach is presented to solve it. The performance of the proposed algorithm is evaluated with the objective value obtained with a linear programming model, on several literature instances. Computational experiments show the good performance of our GA in terms of solution quality, convergence and computation time.

Phase of nasal cycle during sleep tends to be associated with sleep stage

The phenomena of periodic cycles of vascular engorgement on the nasal cavity mucosa that alternate between right and left sides are termed the "nasal cycle." The physiologic mechanisms underlying this cycle have not been entirely clarified, even more so during sleep. In this study, we measured the periodic patterns of the normal nasal cycle, not only during wakefulness but also during sleep. Our team utilized a method for functional rhinologic assessment, the portable rhinoflowmeter (Rhinocycle, Rhinometrics, Lynge, Denmark), measuring airflow independently through each nostril during 24 hours on 20 healthy subjects aged 20 to 56 years, and without any nasal pathology or diagnosed medical, psychiatric, or sleep disorders. In addition, a nocturnal polysomnogram was simultaneously performed during sleep. Nineteen of 20 subjects showed a detectable nasal cycle, and 16 of 19 subjects presented a change of the cyclic phase during sleep. The mean nasal cycle duration was 234.2 ± 282.4 minutes (median, 164.1 minutes), although variation was considerable. The mean cycle duration time during sleep was significantly longer than that in wakefulness (P <0.005). The reversal of cyclic phase during sleep tended to be associated with REM sleep (68.8%) and postural changes (18.8%). It never occurred in slow-wave sleep. Nasal cycle duration during sleep is longer than in wakefulness. Changes in laterality of nasal cycle frequently coincide with switches in posture, tend to occur in REM sleep, never occur in slow-wave sleep, and may be absent in subjects with severe nasal septal deviations.

Cluster-based exposure variation analysis

BackgroundStatic posture, repetitive movements and lack of physical variation are known risk factors for work-related musculoskeletal disorders, and thus needs to be properly assessed in occupational studies. The aims of this study were (i) to investigate the effectiveness of a conventional exposure variation analysis (EVA) in discriminating exposure time lines and (ii) to compare it with a new cluster-based method for analysis of exposure variation.MethodsFor this purpose, we simulated a repeated cyclic exposure varying within each cycle between “low” and “high” exposure levels in a “near” or “far” range, and with “low” or “high” velocities (exposure change rates). The duration of each cycle was also manipulated by selecting a “small” or “large” standard deviation of the cycle time. Theses parameters reflected three dimensions of exposure variation, i.e. range, frequency and temporal similarity.Each simulation trace included two realizations of 100 concatenated cycles with either low (ρ = 0.1), medium (ρ = 0.5) or high (ρ = 0.9) correlation between the realizations. These traces were analyzed by conventional EVA, and a novel cluster-based EVA (C-EVA). Principal component analysis (PCA) was applied on the marginal distributions of 1) the EVA of each of the realizations (univariate approach), 2) a combination of the EVA of both realizations (multivariate approach) and 3) C-EVA. The least number of principal components describing more than 90% of variability in each case was selected and the projection of marginal distributions along the selected principal component was calculated. A linear classifier was then applied to these projections to discriminate between the simulated exposure patterns, and the accuracy of classified realizations was determined.ResultsC-EVA classified exposures more correctly than univariate and multivariate EVA approaches; classification accuracy was 49%, 47% and 52% for EVA (univariate and multivariate), and C-EVA, respectively (p < 0.001). All three methods performed poorly in discriminating exposure patterns differing with respect to the variability in cycle time duration.ConclusionWhile C-EVA had a higher accuracy than conventional EVA, both failed to detect differences in temporal similarity. The data-driven optimality of data reduction and the capability of handling multiple exposure time lines in a single analysis are the advantages of the C-EVA.

Method of the production cycle duration time modeling within hard coal longwall faces / Metoda probabilistycznego modelowania czasu trwania czynności cyklu produkcyjnego realizowanego w przodkach ścianowych kopalń węgla kamiennego

Method of probabilistic modeling of the production cycle duration time within hard coal longwall faces has been described in the present study. Duration of these activities for various technologies, including probabilistic schemes modeling have been described in the introduction. In order to illustrate the described method, an example of probabilistic modeling for data obtained from specific longwall face has been presented. The final chapters entitled “The possibility of Using the method” and “Results” contain information on the perspective of the method application in mining industry.

Realization of a micrometre-sized stochastic heat engine

The conversion of energy into mechanical work is essential for almost any industrial process. The original description of classical heat engines by Sadi Carnot in 1824 has largely shaped our understanding of work and heat exchange during macroscopic thermodynamic processes1. Equipped with our present-day ability to design and control mechanical devices at micro- and nanometre length scales, we are now in a position to explore the limitations of classical thermodynamics, arising on scales for which thermal fluctuations are important2,3,4,5. Here we demonstrate the experimental realization of a microscopic heat engine, comprising a single colloidal particle subject to a time-dependent optical laser trap. The work associated with the system is a fluctuating quantity, and depends strongly on the cycle duration time, τ, which in turn determines the efficiency of our heat engine. Our experiments offer a rare insight into the conversion of thermal to mechanical energy on a microscopic level, and pave the way for the design of future micromechanical machines.

Processing of Integral-Skin Cellular Polymeric Composites in Rapid Rotational Foam Molding

In order to survive the competition, the processing cycle time and the energy consumption of the rotational foam molding process must be reduced to a fraction of its current levels without compromising product quality. This paper introduces a novel extrusion-assisted rotational foam molding process for the manufacture of rotational moldings having adjacent, but clearly distinct, layers of an integrated solid (non-cellular) skin boundary layer encapsulating a cellular core structure, consisting of identical or compatible polyolefin grades, that achieves significant savings in processing cycle time duration and energy consumption. It introduces non-chilled extruded foam as a foamed core-forming material, in real time, directly into a uni-axially rotating hot mold through a dedicated mold “injection” port onto the already formed un-foamed soft skin layer.

Application of Mixed Oxide Catalysts to the Removal of Lean NO&lt;SUB&gt;&lt;I&gt;x&lt;/I&gt;&lt;/SUB&gt; and N&lt;SUB&gt;2&lt;/SUB&gt;O Using Transient-Mode Cyclic Operations

The storage and reduction of NO and N2O in the presence of excess O2 have been investigated over two mixed oxide catalysts. The catalysts, which were prepared via coprecipitation of solutions of mixed metal nitrates, followed by calcination, were found to have plenty storage capacities for nitrogen oxides. The storage and reduction performances varied with the catalyst composition and the duration of cycle time: the AlCoPd (1/1/0.05) mixed oxide catalyst exhibited higher efficiency for NO, and an AlCoFe (1/1/2) mixed oxide catalyst exhibited higher efficiency for N2O. The adsorptions of NO and N2O onto the mixed oxide catalysts progressed without an oxidation step, and the adsorptivity of NO surpassed that of O2. The mixed oxides showed spinel structures with sizes of 10-100 nm, and with well-developed mesopores that were formed by the evaporation of H2O and CO2 from layered double hydroxide (LDH) precursors. The storage and reduction of lean NOx and N2O over the mixed oxide catalysts were carried out via cyclic operations in a transient mode at 300 degrees C and at space velocities of around 30,000 h(-1). The removal efficiency of the cyclic operations generally increased with reduced adsorption cycle time, and reached 90% for NOx and N2O with the respective catalysts.

A simple smart wing actuator using Ni-Ti SMA

One way shape memory effect (SME) is not sufficient in the application of the automatic repeated actuation of the SMA wire because the actuator using SME cannot return to its initial shape after it cools down. In the present study, the two-way SME under residual stress is considered. An actuator using the two-way effect of SMA returns to its initial shape by increasing or decreasing the temperature of SMA under initial residual stress. Using the two-way effect, we manufactured a simple smart wing actuator which consists of the SMA wire and a torsional spring to induce variable residual stresses. The SMA wire after the specific training procedure in order for the actuator to be used for the repeated actuations without performance deteriorations in the specified actuation requirements was used. The simple smart wing actuator has been tested for repeated actuations in still-air as an environmental thermal condition for the practical aspect of its usage. The characteristics of actuator behavior according to operation thermal cycle duration time, i.e., the response characteristics for rapid actuation were investigated. By the application of the simple smart wing actuator using the SMA wire, SMA shows novel performance in repeated actuations.

Relative influence of injection molding processing conditions on HDPE acetabular cups dimensional stability

The effects of processing conditions on the characteristics of injection-molded high density polyethylene (HDPE) acetabular cups for the total hip replacement implants have been studied. The study has been focused on the effects of filling rate (injection speed), packing pressure, packing time and hot nozzle temperature of the mold on the dimensional stability, weight variation and visual appearance of the acetabular cups. A considerable influence of these processing conditions on the weight and dimension variation was found. Information regarding cycle time duration was obtained through numerical simulation of the entire molding process using a commercial dedicated code Moldflow Plastics Insight 6.1 (Moldflow Corporation, 2007). Within the influencing process parameters studied, the packing pressure was found to be the most significant one affecting the part dimensions and weight. An increase in the injection speed (decrease in the injection time) had a negative effect on the weight and on the most of the part’s analyzed dimensions. The influence of the hot nozzle temperature and packing time was considered irrelevant, for the range of process parameters under analysis. For all the set-point variation tests, two singularities on the linear dimension variations were identified: anisotropic shrinkage in flow and normal to flow direction and a slight plastic expansion at the location around the hall furthest away from the injection point.

THE EFFECTS OF MOVEMENT VELOCITY DURING SQUATTING ON ENERGY EXPENDITURE AND SUBSTRATE UTILIZATION IN WHOLE-BODY VIBRATION

The purpose of this study was to examine whether and how cycle time duration affects energy expenditure and substrate utilization during whole-body vibration (WBV). Nine men performed 3 squatting exercises in execution frequency cycles of 6, 4, and 2 seconds to 90° knee flexion with vibration (Vb-) (frequency was set at 30 Hz and the amplitude of vibration was 4 mm) and without vibration (Vb-) during 3 minutes, each with an additional load of 30% of the subject's body weight. A 2-way analysis of variance for O2 revealed a significant vibration condition main effect (p < 0.001) and a cycle time duration effect (p < 0.001). When differences were analyzed by Fisher's LSD test, cycle time duration of 2 seconds was significantly different from 4 and 6 seconds, both in Vb+ and Vb-. Total energy expenditure (EEtot), carbohydrate oxidation rate (EEcho), and fat oxidation rate (EEfat) demonstrated a significant vibration condition main effect (EEtot: p < 0.01; EEcho: p < 0.001; EEfat: p < 0.001) and cycle time duration main effect (EEtot and EEcho: p < 0.001; EEfat: p < 0.01). EEtot,EEcho, and EEfat post hoc comparisons indicated that values for the 2-second test significantly differed from 4 and 6 seconds when compared in the same vibration condition. O2 and EE values were greater in Vb+ than in Vb-conditions with the same cycle time duration. Our study confirms that squatting at a greater frequency helps to maximize energy expenditure during exercise with or without vibration. Therefore, cycle time duration must be controlled when vibration exercise is prescribed.

The Effects of Movement Velocity During Squatting on Energy Expenditure and Substrate Utilization in Whole-Body Vibration

The purpose of this study was to examine whether and how cycle time duration affects energy expenditure and substrate utilization during whole-body vibration (WBV). Nine men performed 3 squatting exercises in execution frequency cycles of 6, 4, and 2 seconds to 90 degrees knee flexion with vibration (Vb+) (frequency was set at 30 Hz and the amplitude of vibration was 4 mm) and without vibration (Vb-) during 3 minutes, each with an additional load of 30% of the subject's body weight. A 2-way analysis of variance for VO2 revealed a significant vibration condition main effect (p < 0.001) and a cycle time duration effect (p < 0.001). When differences were analyzed by Fisher's LSD test, cycle time duration of 2 seconds was significantly different from 4 and 6 seconds, both in Vb+ and Vb-. Total energy expenditure (EE(tot)), carbohydrate oxidation rate (EE(cho)), and fat oxidation rate (EE(fat)) demonstrated a significant vibration condition main effect (EE(tot): p < 0.01; EE(cho): p < 0.001; EE(fat): p < 0.001) and cycle time duration main effect (EE(tot) and EE(cho): p < 0.001; EE(fat): p < 0.01). EE(tot), EE(cho), and EE(fat) post hoc comparisons indicated that values for the 2-second test significantly differed from 4 and 6 seconds when compared in the same vibration condition. VO2 and EE values were greater in Vb+ than in Vb- conditions with the same cycle time duration. Our study confirms that squatting at a greater frequency helps to maximize energy expenditure during exercise with or without vibration. Therefore, cycle time duration must be controlled when vibration exercise is prescribed.