Experimental study on thermal decomposition kinetics of natural ageing AP/HTPB base bleed composite propellant

The kinetics of the thermal decomposition for a naturally ageing ammonium perchlorate(AP) and hydroxyl-terminated-polybutadiene(HTPB) base bleed composite propellant were investigated using a differential scanning calorimetry(DSC). The naturally ageing AP/HTPB base bleed propellant samples have been stored in a sealed plastic bag at room temperature(5-25 ℃) for more than 20 years. The experimental DSC results were obtained by placing samples(each about 1.5 mg) in a sealed pan under non-isothermal condition under different heating rates, 5.0, 10.0, 15.0, 20.0 and 30.0 ℃·min^(-1). The activation energy and pre-exponential factor were estimated based on the relationship between the exothermic peak temperature and the heating rate by Ozawa and Kissinger methods, respectively. The decomposition kinetic parameters is lower the values under laboratorial aging condition.

An Experimental Simulation of Load-Leveling Through Adsorption for Natural Gas Pipeline System

A load-leveling method through adsorption was presented to adjust the supply quantity according to the consumption rate of natural gas with time. An experimental simulation set up was designed and used to test the load-leveling function for a real pipeline system. A storage tank filled with activated carbon together with a filter constitutes the major part of the load-leveling facility. Pressure and temperature of the system, as well as the real gas output of the storage tank were recorded. It is proven that load-leveling by adsorption is technically feasible even for low pipeline pressure of natural gas supply system.

Experimental investigation of chimney-enhanced natural convection in hexagonal honeycombs

The natural convective heat transfer performance of an aluminum hexagonal honeycomb acting as a novel heat sink for LED cooling is experi- mentally investigated. The concept of adding an adiabatic square chimney ex- tension for heat transfer enhancement is proposed, and the effects of chimney shape, height, and diameter are quantified. The average Nuav of a heated hon- eycomb with straight chimney is significantly higher than that without chimney, and the enhancement increases with increasing chimney height. At a given chim- ney height, honeycombs with divergent chimneys perform better than those with convergent ones. For a fixed divergent angle, the Nuav number increases mono- tonically with increasing chimney height. In contrast, with the convergent angle fixed, there exists an optimal chimney height to achieve maximum heat transfer.

Experimental Study of Tunnel Fire with Natural Ventilation

The 1/15 reduced-scale experiments using Froude scaling were designed to study the effect on the smoke control efficiency for subway tunnel fires with natural ventilation mode.The propane gas fires with heat release rate 11.48 kW was used,which corresponds to the heat release rate 10 MW in the full-scale tunnel.The temperature distributions under the ceiling were measured by K-type thermocouples to investigate smoke movement,and the velocity of smoke in shafts was measured by hot-wire anemometer to obtain the smoke extract amount of ventilation shafts.The results show that the smoke temperature under the ceiling varies with the longitudinal different distance from fire source.The results also show that the smoke temperature distributions and the smoke control efficiency in tunnel vary with the space between ventilation shafts and vary with the area and the height of ventilation shaft.

Natural Monopoly and Mixed Ownership Reform--Based on Natural Experiment and Cost Function Analysis Method

Despite a multitude of theoretical discussions on China's mixed ownership reform, very few studies have addressed realistic questions concerning the implementation of the reform. The Resolutions of the Third Plenum of the 18 th CPC Central Committee and other reform strategies have outlined the reform of sectors with natural monopoly, including urban public utility sectors. The question is how mixed ownership reform should be carried out in sectors of natural monopoly, or which public utilities sectors should enjoy priority of mixed ownership reform. To answer this question, this paper employs data of large public utility enterprises in China from 1998 to 2008, and estimates the natural monopoly attribute at the industry level and corporate total factor productivity(TFP) using cost function analysis method excluding the impact of product price factor. Based on the difference-indifferences-in-differences(DDD) method of natural experiment, an empirical test is carried out for the relationship among natural monopoly, mixed ownership reform and corporate productivity. Our results suggest that:(1) Statistically, mixed ownership reform cannot significantly increase corporate TFP in sectors with natural monopoly;(2) mixed ownership reform should not be carried out indiscriminately on a nationwide basis and for all public utilities sectors. Such an attempt of reform without distinguishing natural monopoly and the level of competitiveness is fraught with policy uncertainties;(3) relative to sectors with natural monopoly, corporate productivity in competitive sectors after mixed ownership reform will improve more significantly and enjoy greater "policy dividends" of institutional reform. Therefore, mixed ownership reform should be carried out first in competitive sectors.

Mechanisms of carbon isotopic fractionation in the process of natural gas generation: Geochemical evidence from thermal simulation experiment

Low maturity coal samples were taken from the Ordos Basin to conduct gold tube thermal simulation experiment in a closed system,and the characteristics of the products were analyzed to find out the fractionation mechanism of carbon isotopes and the causes of abnormal carbon isotopic compositions of natural gas.At the heating rates of 2℃/h(slow)and 20℃/h(rapid),the low maturity coal samples of the Ordos Basin had the maximum yields of alkane gas of 302.74 mL/g and 230.16 mL/g,theδ13C1 ranges of-34.8‰to-23.6‰and-35.5‰to-24.0‰;δ13C2 ranges of-28.0‰to-9.0‰and-28.9‰to-8.3‰;andδ13C3 ranges of-25.8‰to-14.7‰and-26.4‰to-13.2‰,respectively.Alkane gas in the thermal simulation products of rapid temperature rise process showed obvious partial reversal of carbon isotope series at 550℃,and at other temperatures showed positive carbon isotope series.In the two heating processes,theδ13C1 turned lighter first and then heavier,and the non-monotonic variation of theδ13C1 values is because the early CH4 is from different parent materials resulted from heterogeneity of organic matter or the carbon isotope fractionation formed by activation energy difference of early enriched 12CH4 and late enriched 13CH4.The reversal of carbon isotope values of heavy hydrocarbon gas can occur not only in high to over mature shale gas(oil-type gas),but also in coal-derived gas.Through thermal simulation experiment of toluene,it is confirmed that the carbon isotope value of heavy hydrocarbon gas can be reversed and inversed at high to over mature stage.The isotope fractionation effect caused by demethylation and methyl linkage of aromatic hydrocarbons may be an important reason for carbon isotope inversion and reversal of alkane gas at the high to over mature stage.

Natural orifice transluminal endoscopic surgery in urology: The Chinese experience

Objective:To describe the Chinese experience of natural orifice transluminal endoscopic surgery(NOTES)in urology.Methods:From December 2008 to May 2017,35 animal experiments and 305 clinical surgeries of NOTES or natural orifices specimen extractions(NOSE)were performed in China.The animal experiments included five kidney biopsies,24 nephrectomies and six partial nephrectomies.The clinical surgeries included 12 transvaginal NOSE(TV-NOSE),266 hybrid transvaginal NOTES(TV-NOTES)and 27 pure TV-NOTES.The TV-NOSE procedure was performed in five transumbilical laparoendoscopic single-site(U-LESS)nephrectomies,four suprapubic-assisted laparoendoscopic single-site surgery(SA-LESS)nephroureterectomies,and three laparoscopic radical cystectomies.The hybrid TV-NOTES procedure included 210 nephrectomies,31 adrenalectomies,eight nephroureterectomies,13 partial nephrectomies,and four heminephrectomies.The pure TV-NOTES procedure included five renal cyst decortications and 22 nephrectomies.Results:A total of 29 animal experiments were successfully performed.One partial nephrectomy was converted to standard laparoscopic surgery.Two kidney biopsies and two nephrectomies were unsuccessful.A total of 297 clinical surgeries were successfully performed.Six patients who underwent hybrid TV-NOTES were converted to open surgery.Two patients who underwent pure TV-NOTES were converted to SA-LESS.There were 22 major complications,16 occurred intraoperatively and six postoperatively.The mean visual analog score(VAS)of 48 h after the operation was 2.5 points in TV-NOSE,2.3 points in hybrid TV-NOTES and 1.7 points in pure TV-NOTES.The mean follow-up of 50.6(3.0-87.0)months showed that all patients were in good condition.The umbilicus scars were nearly invisible in TV-NOSE and hybrid TV-NOTES.The vaginal incision healed well.Conclusions:TV-NOSE and TV-NOTES are feasible,safe,and effective with little injury,low pain,fast recovery,and good cosmetic outcomes in properly selected patients.They are worth consideration for urological clinical practice.

Planning and Design of Zhengzhou Forest Park Based on Natural Ecological Experience

Through summarizing and analyzing planning objectives, landscape division and natural ecological experience planning of Zhengzhou Forest Park, the authors discussed the application of human-nature harmony in the planning, stressed citizens' needs for experiencing natural ecological environment, and tried to build Zhengzhou Forest Park with picturesque scenery, complete facilities, and harmonious human-nature coexistence.

A Quasi Experiment to Implement Multimodal Strategy to Improve Hand Hygiene Behavior in a Healthcare Facility in Central Saudi Arabia

Background: Hand hygiene (HH) compliance of healthcare workers (HCWs) remains suboptimal despite standard multimodal promotion, and evidence for the effectiveness of novel interventions is urgently needed. Aim: Improve HCWs’ HH compliance toward minimizing healthcare associated infection (HCAI) risk in Wadi Al Dawasir Hospital (WDH), central Kingdom of Saudi Arabia (KSA). Methodology: A quasi experimental approach was adopted to achieve study aim. The HCWs’ behavior of HH during the duration between 2015 and 2016 was evaluated before and after a HH educational plan based on the World Health Organization (WHO) “Multimodal HH Improvement Strategy” (MMHHIS). The HCWs’ compliance in response to HH indications represented by the WHO’s “My 5-Moments for HH” and the type of HH action taken, whether hand washing (HW) or hand-rubbing (HR) were analyzed. Results: The number of opportunities observed of HH performance accounted 230 in 2015 (pre-education), and 237 in 2016 (post-education). The HCWs’ HH compliance rate in the pre-education phase did not vary by the 5-moment indications [χ2(df 4) = 0.01, p = 0.98]. Conversely, the compliance rate after HH education was higher than non-compliance across all 5-moment indication opportunities (ranged between 57.0% up to 88.9%) [χ2(df 1) = 18.25, p rd and 4th 5-moment indications (“after body fluid exposure” and “after patient contact,” respectively) were met with a significant HH improvement [χ2(df 1) = 8.98, p = 0.003;and χ2(df 1) = 16.3, p −4.38, p = 0.001). Only physicians and nurses showed a significant “within-profession” improvement in HH compliance after education, compared to that before education (Z = −3.51, p = 0.001, Z = −2.48, p = 0.013, respectively). Conclusions: Applying a HH education plan based on standardized multimodal HH strategy proved effective in improving the HH compliance of the hospital’s staff. An ongoing observation policy within a HH-resourceful environment assures a sustainable and sound HCWs’ HH behavior.

Current Implementation and Experience of Natural Farming in Japan

The natural farming in Japan mainly includes Mokich Okadas natural farming theory and Masanobu Fukuokas natural farming theory in terms of genre.Natural farming was proposed and implemented to deal with the anabatic soil degradation and food safety problems.Among themꎬMokich Okadas natural farming theory advocates the restoration of the agricultural tradition of the past and combination with modern agricultural science and technologyꎻMasanobu Fukuokas natural farming theory advocates a complete return to natural and traditional farming and puts forward a set of green agricultural cultivation methods focusing on injurious insect control with beneficial insectꎬweed control with green herbaceous plantsꎬsoil reclamation with grassꎬnontoxic and cost￣reducing method based on the Japanese ancient agricultural books.Their natural farming theories have been widely popularized and applied in Japanꎬand its successful experience is worthy of study and reference for China.

A Quasi-Experimental Study of English Vocabulary Teaching Based on Incidental Acquisition

Recent years have witnessed a phenomenon that major English teachers in China have adopted the traditional teaching pattern, mechanically linking English pronunciations directly with the meaning of Chinese, which gradually dampens learners’ enthusiasm. The chief purpose of this paper was to design one English vocabulary teaching lesson based on incidental acquisition. More specifically, the questions raised are, on the one hand, whether incidental vocabulary teaching imprints differences on the learning outcomes for middle school students, and, on the other hand, whether incidental acquisition results in positive feedback between teachers and students. The technique we applied was referred to as questionnaires and interviews addressed to a sample of 68 students. Focusing on the effect of incidental vocabulary acquisition, the analysis demonstrated that it could enhance students’ vocabulary capacity. In addition, it was interesting to note that excellent students and average students tended to embrace the new teaching style while underachievers were on the opposite side. On this basis, it is recommended for English teachers to design English vocabulary lessons, adopting visual, auditory, oral, reading or writing training. More precisely, they should use phonics rules and patterns, holistic learning, classified vocabulary teaching, visual illustration or multimedia teaching to give lessons effectively and expand learners’ vocabulary.

Effect of Methane Gas on Acoustic Characteristics of Hydrate-Bearing Sediment–Model Analysis and Experimental Verification

Gas leakage is an important consideration in natural systems that experience gas hydrate accumulation.A number of velocity models have been created to study hydrate-bearing sediments,including the BGTL theory,the weighted equation,the Wood equation,the K-T equation,and the effective medium theory.In previous work,we regarded water as the pore fluid,which meant its density and bulk modulus values were those of water.This approach ignores the presence of gas,which results in a biased calculation of the pore fluid's bulk modulus and density.To take into account the effect of gas on the elastic wave velocity,it is necessary to recalculate the bulk modulus and density of an equivalent medium.Thus,a high-pressure reactor device for simulating leakage systems was developed to establish the relationship between wave velocity and hydrate saturation in methane-flux mode.A comparison of the values calculated by the velocity model with the experimental data obtained in this study indicates that the effective medium theory(EMT,which considers gas effects)is more applicable than other models.For hydrate saturations of 10%–30%,the result ranges between EMT-B(homogenous gas distribution)and EMT-B(patchy gas distribution).For hydrate saturations of 30%–60%,the results are similar to those of the EMT-B(homogenous gas distribution)mode,whereas hydrate saturations of 60%–70%yield results similar to those of the EMT-A mode.For hydrate saturations greater than 80%,the experimental results are similar to those of the EMT-B mode.These results have significance for hydrate exploitation in the South China Sea.

Natural consolidation characteristics of viscous debris flow deposition

Pore water pressure and water content are important indicators to both deposition and consolidation of debris flows, enabling a direct assessment of consolidation degree. This article gained a more comprehensive understanding about the entire consolidation process and focused on exploring pore water pressure and volumetric water content variations of the deposit body during natural consolidation under different conditions taking the viscous debris flow mass as a study subject and by flume experiments. The results indicate that, as the color of the debris changed from initial dark green to grayish-white color, the initial deposit thickness declined by 3% and 2.8% over a permeable and impermeable sand bed, respectively. A positive correlation was observed between pore water pressure and depth in the deposit for both scenarios, with deeper depths being related to greater pore water pressure. For the permeable environment, the average dissipation rate of pore water pressure measured at depths of 0.10 m and 0.05 m were 0.0172 Pa/d and 0.0144 Pa/d, respectively, showing a positivechanging trend with increasing depth. Under impermeable conditions, the average dissipation rates at different depths were similar, while the volumetric water content in the deposit had a positive correlation with depth. The reduction of water content in the deposit accelerated with depth under impermeable sand bed boundary conditions, but was not considerably correlated with depth under permeable sand bed boundary conditions. However, the amount of discharged water from the deposit was greater and consolidation occurred faster in permeable conditions. This indicates that the permeability of the boundary sand bed has a significant impact on the progress of consolidation. This research demonstrates that pore water and pressure dissipations are present during the entire viscous debris consolidation process. Contrasting with dilute flows, pore pressure dissipation in viscous flows cannot be completed in a matter of minutes or even hours, requiring longer completion time — 3 to 5 days and even more. Additionally, the dissipation of the pore water pressure lagged the reduction of the water content. During the experiment, the dissipation rate fluctuated substantially, indicating a close relationship betweenthe dissipation process and the physical properties of broadly graded soils.

Experimental Studies on Sloshing Mitigation Using Dual Perforated Floating Plates in A Rectangular Tank

The performance of dual perforated floating plates in a rectangular tank is investigated based on the model tests under different external excitations for different filling rates.It is found that dual perforated floating plates in the tank can remarkably mitigate violent resonant sloshing responses compared with the clean tank,especially when the external excitation frequency is in the vicinity of the first-order resonant frequency.Next,the parametric studies based on different filling rates and external excitation amplitudes are performed for the first-order resonant frequencies.The presence of dual perforated floating plates seldom shifts the sloshing natural frequencies.Further,dual perforated floating plates change the sloshing modes from the standing-wave mode in the clean tank to the Utube mode,which can arise from the sloshing reduction to some extent.

Experimental Study of Effect of Vents in Thermal Ventilation

The effects of vents on thermal ventilation to save energy in the cold rolling workshop of Baosteel were investigated.According to the scale modeling theory,a small chamber was established.The details about construction of experiment on thermal ventilation and the preparation and arrangement of apparatus were discussed,and then the effects of vents on thermal ventilation were studied through experiments,which includes the temperature distribution,the volume of ventilation,the temperature difference between inlets and outlets,the neutral plane,and the effective thermal coefficient of thermal natural ventilation.Based on this,the effects of natural ventilation based on varied area of inlets and outlets and those of vents on one side and on different sides were compared.According to the experiments,the area of inlet vents and outlet vents affect the temperature distribution in chamber,and their effects on ventilation volume are different,but the effects of vents in single side or different sides are the same under the condition that only thermal ventilation is considered.

Heat Transfer Characteristics of Square Micro Pin Fins under Natural Convection

In order to comply with the recent demand for downsizing of the electric equipment, the minia- turization and the improvement in heat transfer performance of a heat sink under natural air-cooling are increasingly required. This paper describes the experimental and numerical investigations of heat sinks with miniature/micro pins and the effect of the pin size, pin height and the number of pins on heat transfer characteristics of heat sinks. Five types of basic heat sink models are investigated in this study. The whole heat transfer area of heat sinks having the different pin size, pin height and the number of pins respectively is kept constant. From a series of experiments and numerical analyses, it has been clarified that the heat sink temperature rises with increase in the number of pins. That is, the heat sink with miniaturized fine pins showed almost no effect on the heat transfer enhancement. This is because of the choking phenomenon occurred in the air space among the pin fins. Reflecting these results, it is confirmed that the heat transfer coefficient reduces with miniaturization of pins. Concerning the effects of the heat transfer area on the heat sink performance, almost the same tendency has been observed in other three series of large surface area, that is, higher pin height. Furthermore as a result of studying non-dimensional convection heat transfer performance, it was found that the relation between the Nusselt number (Nu) and the Rayleight number (Ra) is given by Nu = 0.16 Ra0.52.

Interpretation of Nature:A Comparison of the Influence of Childhood Experience on William Wordsworth and John Ruskin

Since childhood,William Wordsworth and John Ruskin have developed a very natural love for landscape and scenery.Although they have different ways to interpret what they see and how they feel,they both stick to their genuine feelings without pre⁃tension in their poems.Those unpretentious feelings and behaviors,which are crucial to their later development to be remarkable artists,come from their original habit and attitude towards Nature as a child.All their life,they preserved this innocence in their work as a memory of childhood.

The generation kinetics of natural gases in the Kela-2 gas field from the Kuqa Depression, Tarim Basin, northwestern China

The Kela-2 gas field, found in the Kuqa Depression of the Tarim Basin, northwestern China, is a large-sized dry gas field (C1 /C1-5 =0.992 0.999) and characterized by ultra-high pressure (pressure factor up to 2.0 2.2). The pyrolysis experiment was carried out under isothermal gold-tube closed system, with samples collected from the Jurassic coal, Jurassic mudstone and Triassic mudstone in the Kuqa Depression. The result of gas yield showed that the Middle and Lower Jurassic source rocks have higher gas generation potential than the Triassic source rocks. The kinetic modeling of gas generation and methane carbon isotope fractionation suggested that the Kela-2 gases belong to the products of high-over mature stages and were mainly derived from the Middle and Lower Jurassic coal-bearing strata. The Triassic source rocks made a minor contribution to the Kela-2 gases. The Kela-2 gases chiefly generated from coal-bearing source rocks with R o values from 1.3% to 2.5%, and thus primarily accumulated after 5 Ma.

Application of Natural Language Processing in Virtual Experience AI Interaction Design

This paper investigates the application of Natural Language Processing (NLP) in AI interaction design for virtual experiences. It analyzes the impact of various interaction methods on user experience, integrating Virtual Reality (VR) and Augmented Reality (AR) technologies to achieve more natural and intuitive interaction models through NLP techniques. Through experiments and data analysis across multiple technical models, this study proposes an innovative design solution based on natural language interaction and summarizes its advantages and limitations in immersive experiences.

Quasi-Regression基函数的选择和算法改进

Quasi-Regression主要用于解决高维空间的函数逼近问题 .函数的拟合效果依赖于所选择的标准正交基函数和拟合算法 .在很多情况下 ,未知函数可以表示成若干个部分变量的函数和 .本文对此提出了一种函数的拟合算法 ,通过对这些部分变量的函数的拟合 ,得到原函数的拟合 ,并且说明新方法精度更高 ,计算量更少 .