Constant Duration Research Articles

Climate drivers of adult insect activity are conditioned by life history traits.

Insect phenological lability is key for determining which species will adapt under environmental change. However, little is known about when adult insect activity terminates and overall activity duration. We used community-science and museum specimen data to investigate the effects of climate and urbanisation on timing of adult insect activity for 101species varying in life history traits. We found detritivores and species with aquatic larval stages extend activity periods most rapidly in response to increasing regional temperature. Conversely, species with subterranean larval stages have relatively constant durations regardless of regional temperature. Species extended their period of adult activity similarly in warmer conditions regardless of voltinism classification. Longer adult durations may represent a general response to warming, but voltinism data in subtropical environments are likely underreported. This effort provides a framework to address the drivers of adult insect phenology at continental scales and a basis for predicting species response to environmental change.

An adaptive shock mitigation control method for helicopter seat system with magnetorheological energy absorbers

This research presents a minimal maximum deceleration (MMD) control method which can be used in the shock mitigation system with magnetorheological energy absorbers (MREAs). The proposed control method can make the payload stop at the end of the available MREA stroke with the lowest maximum deceleration, which does not exceed the deceleration threshold value and lead to the lowest occupant injury probability. The shock mitigation system controlled by MMD will experience constant deceleration control stage and maximum damping force control stage while making full use of the available MREA stroke. The comparative performance of the MMD control method with Bingham number (BN) control, constant deceleration (CD) control and minimum duration deceleration exposure (MDDE) control is shown. Then, the controllable drop velocity range and the required maximum MREA controllable damping force range of MMD control method is calculated. Subsequently, the optimal control method selection criterion among BN control method, CD control method and MMD control method is developed. Finally, the optimal selection criterion is applied to the drop induced shock mitigation system with varying payload velocity, payload mass (occupant type) and the maximum controllable damping force of MREA.

Making Citizenship an Organizing Principle of the US Immigration System: An Analysis of How and Why to Broaden Access to Permanent Residence and Naturalization for New Americans

This paper proposes that the United States treat naturalization not as the culmination of a long and uncertain individual process, but as an organizing principle of the US immigration system and its expectation for new Americans. It comes at a historic inflection point, following the chaotic departure of one of the most nativist administrations in US history and in the early months of a new administration whose executive orders, administrative actions, and legislative proposals augur a different view of immigrants and immigration. The paper examines two main ways that the Biden–Harris administration can realize its immigration, naturalization and integration goals: i.e., by expanding access to permanent residence and by increasing naturalization numbers and rates. First, it proposes administrative and, to a lesser degree, legislative measures that would expand the pool of eligible-to-naturalize immigrants. Second, it identifies three underlying factors—financial resources, English language proficiency, and education—that strongly influence naturalization rates. These factors must be addressed, in large part, outside of and prior to the naturalization process. In addition, it provides detailed estimates of populations with large eligible-to-naturalize numbers, populations that naturalize at low rates, and populations with increasing naturalization rates. It argues that the administration's immigration strategy should prioritize all three groups for naturalization. The paper endorses the provisions of the US Citizenship Act that would place undocumented and temporary residents on a path to permanent residence and citizenship, would reduce family- and employment-based visa backlogs, and would eliminate disincentives and barriers to permanent residence. It supports the Biden-Harris administration's early executive actions and proposes additional measures to increase access to permanent residence and naturalization. It also endorses and seeks to inform the administration's plan to improve and expedite the naturalization process and to promote naturalization. The paper's major findings regarding the eligible-to-naturalize population include the following: In 2019, about 74 percent, or 23.1 million, of the 31.2 million immigrants (that were eligible for naturalization) had naturalized. Three states—Indiana, Arizona, and Texas—had naturalization rates of 67 percent, well below the national average of 74 percent. Fresno, California had the lowest naturalization rate (58 percent) of the 25 metropolitan (metro) areas with the largest eligible-to-naturalize populations, followed by Phoenix at 66 percent and San Antonio and Austin at 67 percent. Four cities in California had rates of 52–58 percent—Salinas, Bakersfield, Fresno, and Santa Maria-Santa Barbara. McAllen, Laredo, and Brownsville had the lowest naturalization rates in Texas. Immigrants from Japan had the lowest naturalization rate (47 percent) by country of origin, followed by four countries in the 60–63 percent range—Mexico, Canada, Honduras, and the United Kingdom. Guatemala and El Salvador each had rates of 67 percent. Median household income was $25,800, or 27 percent, higher for the naturalized population, compared to the population that had not naturalized (after an average of 23 years in the United States for both groups). In the past 10 years, naturalization rates for China and India have fallen, and rates for Mexico and Central America have increased (keeping duration of residence constant). In short, the paper provides a roadmap of policy measures to expand the eligible-to-naturalize population, and the factors and populations that the Biden–Harris administration should prioritize to increase naturalization rates, as a prerequisite to the full integration and participation of immigrants, their families, and their descendants in the nation's life.

Effects of two grip force levels and forearm postures on hand‐arm transmitted vibration and physiological responses

AbstractVibration transmitted to the upper limb is the primary source of occupational musculoskeletal disorder. Transmissibility is not just caused by vibration magnitude but is also directly influenced by the applied force and posture. This study investigated the effects of two forearm postures and grip force levels, when using dual‐handle guided equipment, on hand‐arm transmitted vibration and physiological responses. Sixteen young male adults were recruited. Pre‐task and post‐task assessments including grip strength and perceived discomfort were measured. The task was to hold a vibrating handlebar for 5 ‐min under four randomly sequenced conditions: N/PM/H—neutral/pronated forearm and mild/hard grip. Transmissibility and forearm muscle activities were recorded during each task. It was discovered that neutral posture led to higher wrist and elbow transmissibility, whereas hard grip resulted in higher elbow transmissibility, forearm muscle activities, grip strength reduction, and distal arm discomfort. Furthermore, the interaction between the effects of posture and force significantly influenced wrist extensor activity (NH > PH; NM = PM), proximal arm discomfort (NH < PH; NM = PM), and wrist transmissibility (PH > PM; NH = NM). Essentially, with constant vibration and exposure duration, the application of sustained hard grip had more negative physiological effects because of the greater physical workload toward the hands and forearms. Moreover, gripping hard during pronation led to higher discomfort that reached the proximal arm because a greater effort was required. Hence, a neutral forearm posture is recommended when the tasks require forceful movements and either posture is suggested when less powerful movements are involved.

Remaining Useful Life Prediction of Lithium-Ion Batteries Based on Deep Learning and Soft Sensing

The Remaining useful life (RUL) prediction is of great concern for the reliability and safety of lithium-ion batteries in electric vehicles (EVs), but the prediction precision is still unsatisfactory due to the unreliable measurement and fluctuation of data. Aiming to solve these issues, an adaptive sliding window-based gated recurrent unit neural network (GRU NN) is constructed in this paper to achieve the precise RUL prediction of LIBs with the soft sensing method. To evaluate the battery degradation performance, an indirect health indicator (HI), i.e., the constant current duration (CCD), is firstly extracted from charge voltage data, providing a reliable soft measurement of battery capacity. Then, a GRU NN with an adaptive sliding window is designed to learn the long-term dependencies and simultaneously fit the local regenerations and fluctuations. Employing the inherent memory units and gate mechanism of a GRU, the designed model can learn the long-term dependencies of HIs to the utmost with low computation cost. Furthermore, since the length of the sliding window updates timely according to the variation of HIs, the model can also capture the local tendency of HIs and address the influence of local regeneration. The effectiveness and advantages of the integrated prediction methodology are validated via experiments and comparison, and a more precise RUL prediction result is provided as well.

Impacts of Drying and Rewetting on the Radiocarbon Signature of Respired CO2 and Implications for Incubating Archived Soils

AbstractThe radiocarbon signature of respired CO2 (∆14C‐CO2) measured in laboratory soil incubations integrates contributions from soil carbon pools with a wide range of ages, making it a powerful model constraint. Incubating archived soils enriched by “bomb‐C” from mid‐20th century nuclear weapons testing would be even more powerful as it would enable us to trace this pulse over time. However, air‐drying and subsequent rewetting of archived soils, as well as storage duration, may alter the relative contribution to respiration from soil carbon pools with different cycling rates. We designed three experiments to assess air‐drying and rewetting effects on ∆14C‐CO2 with constant storage duration (Experiment 1), without storage (Experiment 2), and with variable storage duration (Experiment 3). We found that air‐drying and rewetting led to small but significant (α < 0.05) shifts in ∆14C‐CO2 relative to undried controls in all experiments, with grassland soils responding more strongly than forest soils. Storage duration (4–14 y) did not have a substantial effect. Mean differences (95% CIs) for experiments 1, 2, and 3 were: 23.3‰ (±6.6), 19.6‰ (±10.3), and 29.3‰ (±29.1) for grassland soils, versus −11.6‰ (±4.1), 12.7‰ (±8.5), and −24.2‰ (±13.2) for forest soils. Our results indicate that air‐drying and rewetting soils mobilizes a slightly older pool of carbon that would otherwise be inaccessible to microbes, an effect that persists throughout the incubation. However, as the bias in ∆14C‐CO2 from air‐drying and rewetting is small, measuring ∆14C‐CO2 in incubations of archived soils appears to be a promising technique for constraining soil carbon models.

Analyzing the duration frequency and severity of drought using copula function in the Yazd city

Abstract Duration and severity are the two main variables used in drought analysis. The copula functions are appropriate for multivariate drought analysis, as it lacks the limitations of the classical multivariate distribution function. This study investigated the bivariate frequency analysis of drought duration and severity of Yazd city in Iran synoptic station during 1953–2013. To this end, first, the drought duration and severity variables were derived from the 6-month Standardized Precipitation Index. Then, considering the distribution functions, the gamma distribution function was selected for analyzing the severity and the exponential distribution function was selected for analyzing the duration and then the Clayton copula function was selected out of the three copula functions as the most appropriate one. After conducting bivariate frequency analysis, the joint seasonal and conjunctive return period and conditional return period curves were plotted. The current study well signified that multivariate analyses could present better interpretations of the reality; for example, as it was identified in conditional return period curves of the drought, for every constant duration, the amount of the return period changed as the severity changed. On the contrary, in analyzing the univariate of duration, no effects of severity were observed.

Generation of custom acoustic harmonic bursts from spherical helmholtz resonators using Q-switched Nd:YAG laser induced plasma

We present a new method for generating a 4 to 25 ms high power acoustic harmonic bursts, reaching more than 110 dB Sound Pressure Level (SPL), from the spherical Helmholtz resonators. The method uses Q-switched Nd:YAG laser pulses (wavelength = 1064 nm, pulse width = 6 ns, and energy = 450 mJ) to induce plasma shocks inside an AISI 316L stainless steel cavity. The confined plasma shock produces an acoustic burst of temporal standing waves which are characterized by a wide harmonic bandwidth. The frequency response of the system depends on the geometry of the used Helmholtz resonator as well as the laser wavelength (with constant laser pulse duration and fluence). The experiments reveal the dependence of the odd/even harmonic on laser wavelength. This method is a prospective alternative for the dodecahedron loudspeakers, other sources in ISO and standard audio tests.

Referred Orofacial Pain as an Initial Symptom of Distant, Nonmetastatic Cancer: Report of a Case and Review of the Literature

Referred orofacial pain as the first symptom of an otherwise silent distant, nonmetastatic cancer has been reported, but there is sparse literature on the subject. Referred pain may not be considered in the orofacial pain differential diagnosis because of its rarity; however, this may delay a cancer diagnosis. The authors present a case report and a review of the English literature. Peer-reviewed publications were identified through a systematic search of MEDLINE, Embase, and Cochrane CENTRAL. Historic cases were reviewed, and available data regarding demographics, pain characteristics, treatment, cancer diagnosis, and outcome were extracted. Thirty-seven cases were identified. All cancers were intrathoracic. The average age was 54.1 years with a slight female predominance (3:2). Common pain characteristics were (1) diffuse location affecting the ear (76%), jaw (46%), and temple (30%); (2) constant duration (65%); (3) aching quality (74%); (4) severe intensity (94%); and (5) associated systemic symptoms (68%) such as weight loss and digital clubbing. The average time from the onset of facial pain to seeking medical attention was 9 months, and the average time from seeking medication attention to cancer diagnosis was 8 months. Orofacial pain was often attributed to odontogenic (35%) or neuropathic (25%) causes, and treatments for these conditions were also common. The impact of referred orofacial pain on the cancer prognosis was not possible because of the nature of the reviewed studies (case reports with no comparison group). Cancer-associated referred orofacial pain as a first symptom is rare but should be considered in cases with intractable pain and associated systemic symptoms.

B-PO03-131 EFFECTS OF CONTACT FORCE ON LESION SIZE DURING PULSED FIELD ABLATION

Effects of contact force (CF) on lesion formation during pulsed field ablation (PFA) have not been validated. To determine the relationship between average CF and lesion size during PFA using a swine beating heart model. A 7F catheter with a 3.5mm saline irrigated (2ml/min) ablation electrode and CF sensor (TactiCath SE, Abbott) was connected to a pulsed electric field (PEF) generator system (CENTAURI, Galaxy Medical). The catheter was positioned in RV and LV under EnSite guidance in 2 closed chest pigs (66kg). During atrial pacing at 90 bpm, biphasic PEF current was delivered between the ablation electrode and a skin patch at 13 separate sites in RV (28Amp, total pulse width of 1.4ms, 4 pulses synchronized with QRS) and 19 separate sites in LV (35Amp, 1.6ms, 7 pulses) at average CF: 1) low (4-12 g, median 8 g); 2) moderate (16-30 g, median 20 g); or 3) high (33-55 g, median 40 g). Ablation was also performed without electrode contact (2 mm away from the endocardium, confirmed by intracardiac echocardiography, n=5). Pigs were sacrificed at 2 hours after ablation and lesion size was measured using triphenyl tetrazolium chloride (TTC) staining. (Fig.) Ablation lesions were clearly identified with TTC staining, showing the dark central zone surrounded by pale boundaries. At constant PEF current and pulse duration, lesion depth increased significantly with increasing contact force. There were no detectable lesions resulting from ablation without electrode contact. At same PEF dose intensity, lesion depth increases significantly with increasing contact force. Electrode-tissue contact is required for effective lesion formation with PEF ablation.

Duration Comparisons for Vision and Touch Are Dependent on Presentation Order and Temporal Context.

Integrating visual and tactile information in the temporal domain is critical for active perception. To accomplish this, coordinated timing is required. Here, we study perceived duration within and across these two modalities. Specifically, we examined how duration comparisons within and across vision and touch were influenced by temporal context and presentation order using a two-interval forced choice task. We asked participants to compare the duration of two temporal intervals defined by tactile or visual events. Two constant standard durations (700 ms and 1,000 ms in ‘shorter’ sessions; 1,000 ms and 1,500 ms in ‘longer’ sessions) were compared to variable comparison durations in different sessions. In crossmodal trials, standard and comparison durations were presented in different modalities, whereas in the intramodal trials, the two durations were presented in the same modality. The standard duration was either presented first (<sc>) or followed the comparison duration (<cs>). In both crossmodal and intramodal conditions, we found that the longer standard duration was overestimated in <cs> trials and underestimated in <sc> trials whereas the estimation of shorter standard duration was unbiased. Importantly, the estimation of 1,000ms was biased when it was the longer standard duration within the shorter sessions but not when it was the shorter standard duration within the longer sessions, indicating an effect of temporal context. The effects of presentation order can be explained by a central tendency effect applied in different ways to different presentation orders. Both crossmodal and intramodal conditions showed better discrimination performance for <sc> trials than <cs> trials, supporting the Type B effect for both crossmodal and intramodal duration comparison. Moreover, these results were not dependent on whether the standard duration was defined using tactile or visual stimuli. Overall, our results indicate that duration comparison between vision and touch is dependent on presentation order and temporal context, but not modality.

A compact passively Q-switched Tm-Ho codoped crystal laser at 2 µm with narrow pulse duration

A Tm,Ho:YVO4 laser with compact geometry was demonstrated and analyzed. For the continuous wave laser, the slope efficiency of 30.5% was achieved. By inserting a Cr:ZnS saturable absorber into the cavity, the passively Q-switched laser generated almost constant pulse duration of 83 ns with the slope efficiency of 19.3%. The pulse energy was also independent of the pump power, around 130μJ. Through increasing the pump power from 3.7 W to 8.1 W, the pulse repetition varied approximately linearly from 2.9 kHz to 6.8 kHz. The Q-switch efficiency of the PQS laser is up to 58% at the maximum pump power.

Impact of the activation rate of the hyperpolarization- activated current $$\hbox {I}_{\mathrm{h}}$$ on the neuronal membrane time constant and synaptic potential duration

The temporal dynamics of membrane voltage changes in neurons is controlled by ionic currents. These currents are characterized by two main properties: conductance and kinetics. The hyperpolarization-activated current ($I_{\rm h}$) strongly modulates subthreshold potential changes by shortening the excitatory postsynaptic potentials and decreasing their temporal summation. Whereas the shortening of the synaptic potentials caused by the $I_{\rm h}$ conductance is well understood, the role of the $I_{\rm h}$ kinetics remains unclear. Here, we use a model of the $I_{\rm h}$ current model with either fast or slow kinetics to determine its influence on the membrane time constant ($\tau_m$) of a CA1 pyramidal cell model. Our simulation results show that the $I_{\rm h}$ with fast kinetics decreases $\tau_m$ and attenuates and shortens the excitatory postsynaptic potentials more than the slow $I_{\rm h}$. We conclude that the $I_{\rm h}$ activation kinetics is able to modulate $\tau_m$ and the temporal properties of excitatory postsynaptic potentials (EPSPs) in CA1 pyramidal cells. In order to elucidate the mechanisms by which $I_{\rm h}$ kinetics controls $\tau_m$, we propose a new concept called "time scaling factor". Our main finding is that the $I_{\rm h}$ kinetics influences $\tau_m$ by modulating the contribution of the $I_{\rm h}$ derivative conductance to $\tau_m$.

WaveRAPID-A Robust Assay for High-Throughput Kinetic Screens with the Creoptix WAVEsystem.

Surface-based biophysical methods for measuring binding kinetics of molecular interactions, such as surface plasmon resonance (SPR) or grating-coupled interferometry (GCI), are now well established and widely used in drug discovery. Increasing throughput is an often-cited need in the drug discovery process and this has been achieved with new instrument generations where multiple interactions are measured in parallel, shortening the total measurement times and enabling new application areas within the field. Here, we present the development of a novel technology called waveRAPID for a further-up to 10-fold-increase in throughput, consisting of an injection method using a single sample. Instead of sequentially injecting increasing analyte concentrations for constant durations, the analyte is injected at a single concentration in short pulses of increasing durations. A major advantage of the new method is its ability to determine kinetics from a single well of a microtiter plate, making it uniquely suitable for kinetic screening. We present the fundamentals of this approach using a small-molecule model system for experimental validation and comparing kinetic parameters to traditional methods. By varying experimental conditions, we furthermore assess the robustness of this new technique. Finally, we discuss its potential for improving hit quality and shortening cycle times in the areas of fragment screening, low-molecular-weight compound screening, and hit-to-lead optimization.

Choosing the Initial State for Online Replanning

The need to replan arises in many applications. However, in the context of planning as heuristic search, it raises an annoying problem: if the previous plan is still executing, what should the new plan search take as its initial state? If it were possible to accurately predict how long replanning would take, it would be easy to find the appropriate state at which control will transfer from the previous plan to the new one. But as planning problems can vary enormously in their difficulty, this prediction can be difficult. Many current systems merely use a manually chosen constant duration. In this paper, we show how such ad hoc solutions can be avoided by integrating the choice of the appropriate initial state into the search process itself. The search is initialized with multiple candidate initial states and a time-aware evaluation function is used to prefer plans whose total goal achievement time is minimal. Experimental results show that this approach yields better behavior than either guessing a constant or trying to predict replanning time in advance. By making replanning more effective and easier to implement, this work aids in creating planning systems that can better handle the inevitable exigencies of real-world execution.

Battery Charger with Bidirectional Power Transmission

The gradual reduction in price of electric batteries contributes to their wider use in autonomous and centralized power supply systems as a backup source of electricity and increase the share of electric vehicles. In the paper the conditions for increasing the efficiency of electric vehicle batteries, in particular in the framework of the concept of V2G (Vehicle to Grid) as a drive for the organization of autonomous power supply systems are analyzed. It is shown that this is possible only with the simple integration of batteries into the system, flexibility, and a wide range of modes that have to be provided by unified charge-discharge devices. Such charging devices have to have such features: a wide range of input and output voltage parameters; correction of the input power factor; the ability to take the maximum power from renewable energy sources; high energy efficiency. A review of possible topologies for a charger with bidirectional power transmission and a bridge converter with soft switching of transistors at zero voltage, which has a high efficiency, galvanic isolation and the ability to correct the shape of the current. The modes of operation of the converter are analyzed and conditions of soft switching is obtained. It is shown that soft switching is valid for current that is not less than minimal one. Efficiency of the converter with soft commutation is compared with a similar converter with rigid commutation of transistors. It is shown that static losses in converter with soft commutation it higher than in the rigid one. So, the proposed converter should be used if the increase in static losses is compensated by the lack of dynamic losses. Additional feature of the converter is that the regulation of the output voltage of the converter with soft switching is carried out according to the law of frequency-pulse modulation with a constant pause duration, where the pause duration is determined by the period of resonant processes of the converter. The model of the converter in Matlab Simulink is built and it is shown that the efficiency of the proposed converter topology is 10-15% higher, which together with the possibility of sinusoidal current with THD ≈ 20% and two-way transmission energy indicates the feasibility of its use as a charger for electric vehicles under the concept of V2G. However, it should be noted that the use of LCL filter creates a phase shift between voltage and current and degrades the THD value. To improve the shape, it is possible to use specialized laws of modulation [or to use modular converters, which allow to obtain a continuous current shape and reduce the volume of the filter.

Correlation between real-time heart rate and fatigue in chest compression providers during cardiopulmonary resuscitation: A simulation-based interventional study.

Background:The American Heart Association guidelines recommend switching chest compression providers at least every 2 min depending on their fatigue during cardiopulmonary resuscitation (CPR). Although the provider's heart rate is widely used as an objective indicator for detecting fatigue, the accuracy of this measure is debatable.Objectives:This study was designed to determine whether real-time heart rate is a measure of fatigue in compression providers.Study design:A simulation-based prospective interventional study including 110 participants.Methods:Participants performed chest compressions in pairs for four cycles using advanced cardiovascular life support simulation. Each participant's heart rate was measured using wearable healthcare devices, and qualitative variables regarding individual compressions were obtained from computerized devices. The primary outcome was correct depth of chest compressions. The main exposure was the change in heart rate, defined as the difference between the participant's heart rate during individual compressions and that before the simulation was initiated.Results:With a constant compression duration for one cycle, the overall accuracy of compression depth significantly decreased with increasing heart rate. Female participants displayed significantly decreased accuracy of compression depth with increasing heart rate (odds ratio [OR]: 0.97; 95% confidence interval [CI]: 0.95–0.98; P < .001). Conversely, male participants displayed significantly improved accuracy with increasing heart rate (OR: 1.03; 95% CI: 1.02–1.04; P < .001).Conclusion:Increasing heart rate could reflect fatigue in providers performing chest compressions with a constant duration for one cycle. Thus, provider rotation should be considered according to objectively measured fatigue during CPR.

The effect of using nano rice husk ash of different burning degrees on ultra-high-performance concrete properties

This work aims to highlight the effect of seven different types of nano rice husk ash (NRHA) on the mechanical, ultrasonic pulse velocity, and durability of ultra-high-performance concrete (UHPC), whereby two different scenarios were applied. Rice husk ash (RHA) was manufactured by calcining rice husk at temperatures of 300, 500, 700 and 900 °C at a constant time of burning (for 3 h). Then, it was kept for cooling with a constant rate of 100/min and different burning hours of (9, 7, 5, and 3 h, respectively). After that, the product was milled to nano size. The final nano-sized product was added by different dosages (1–5%) with a 2% step to the UHPC mixture. Compressive, splitting tensile, and flexural strength were measured accordingly. Permeability was assessed by the sorptivity test; the ultrasonic pulse velocity test was also conducted. The results showed that the addition of NRHA enhanced the compressive strength and impermeability of UHPC due to the refined pore structure. For a constant burning duration, a significant improvement in compressive strength was observed at a burning temperature of 900 °C and 700 °C for 1% NRHA and at 500 °C and 300 °C for 3% and 5% NRHA. However, for a different burning duration, a significant improvement in compressive strength was recorded at a burning temperature of 700 °C and 500 °C for 3% NRHA, which was burnt for 5 h and 300 °C for 5% NRHA, which was burnt for 9 h. Sorptivity and ultra-sonic pulse velocity confirmed the results. Therefore, the advisable condition is burning at 700 °C for 5 h for more amorphous silica with medium energy compared to other mixes.

Experimental Study on Mechanical Behaviors and Fracture Features of Coarse Marble Specimens after Thermal Shock

Rocks in geothermal reservoirs are often subjected to cyclic thermal shock, the stable operation of the enhanced geothermal system (EGS) is affected by the physical and mechanical properties of rock. There is no sufficient basis for the selection of thermal shock parameters in previous experiments. To this end, this study selected temperature level, constant temperature duration, and thermal shock number as the experimental variables and conducted thermal shock treatment on coarse marble specimens. Then, scanning electron microscope (SEM) tests were used to provide variations in microscopic structure, uniaxial compression tests were carried out, and acoustic emission (AE) technology was applied to investigate the mechanical behaviors and fracture features. The increase of temperature level and the thermal shock number have different degrees of adverse effects on the physical and mechanical properties of rock specimens. The cracks between crystals become larger with the increase of thermal shock number and the crystal structure is gradually destroyed with the elevation of temperature. Two hours is considered as the threshold of constant temperature duration, after which the physical and mechanical properties of specimens stabilize. The temperature level has the greatest influence on crack-initiation stress and crack-damage stress.

A deducing-based reliability optimization for electrical equipment with constant failure rate components duration their mission profile

Recently, with the rapid development of electrical industries, the R&D on electrical equipment has made a massive progress. However, high integration of multiple functions like isolationcircuit breaking, data collection and intelligent control results in low reliabilities. Therefore, a deducing-based reliability optimization for electrical equipment is proposed to enhance the reliability of electrical equipment. The Integrated Isolation Circuit Breaker (IICB), a classical device of power switch, is taken as the object in this research, and the reliability analysis is carried out by building the equipment description model of IICB, bringing forth the deduced method, and taking the constant failure rate components duration their mission profiles as indices for reliability increases. Next, on the basis of the deduced method, the unit to increase the system reliability can be determined. With the guidance of the above method, three kinds of reliability optimization schemes are studied, which are formed in accordance with the topologies of devices, component configurations and redundancy respectively. Finally, the comparing, analyzing and deducing of the three improving schemes are presented respectively. And an example is given to prove that the proposed method is feasible and can effectively improve equipment reliabilities, with valuable guidance for equipment reliability design as well.