“空气的主要性质”教学片段与分析

本文通过问题导入,引导学生提出空气能占有一定的空间的猜想,再选择恰当的工具验证猜想。通过实验的启发,探究空气的主要性质。让学生从旧有的经验出发,顺利展开新的思考。经历有结构的思维过程,明确探究主题和思路。用科学知识解释现象,更是激发了学生们对科学探究的兴趣。把学生的思维角度由面落到点,让材料选择与设计实验在学生头脑中的建构真正符合学生的思维特点和技能水平。培养了学生善于合作、严谨求实的科学精神。

The Application of Pearson Correlational Analysis Method in Air Quality Analysis of Beijing-Tianjin-Hebei Region

Based on the analysis of monitoring data on six pollution indexes of SO2, NO2, CO, O3, PM10 and PM2.5 from 53 monitoring points in 7 cities, including Beijing, Tianjin, Shijiazhuang, etc., from April 8 of 2014 to July 23 of 2014, this article adopted Pearson correlation coefficient method to determine the relevance among each pollutant of these cities with the help of SPSS. The results showed that such three leading indexes as SO2, PM10 and PM2.5 had strong correlation in Beijing, Tianjin and main cities of Hebei. Finally, some suggestions and preventive measures for the cooperative governance of air pollution in Beijing-Tianjin-Hebei Region were put forward, hoping this can help them.

Experimental study on indoor environment improvement in toll booth by personalized ventilation technology

The necessity and feasibility of the use of the personalized ventilation（PV）technology in a toll booth is described.First,the indoor environment of the toll booth equipped with a PV system is analyzed.Based on the analysis results,a set of equipment for controlling the indoor air quality（IAQ）of the toll booth is devised.Then,a full-scale model of the toll booth is set up in the laboratory.The airflow organization,the optimum operation parameters,and the restraint effects of the PV system on pollution are also experimentally studied.The experimental results on the air supply characteristics show that the PV system can effectively reduce the air age,improve the ventilation efficiency,and enhance the comfort and acceptability of human beings.In addition,this system plays a significant role in preventing pollution.

Iron-incorporated nitrogen-doped carbon materials as oxygen reduction electrocatalysts for zinc-air batteries

The application of electrocatalysts for the oxygen reduction reaction(ORR) is vital in a variety of energy conversion technologies. Exploring low-cost ORR catalysts with high activity and long-term stability is highly desirable, although it still remains challenging. Herein, we report a facile and reliable route to convert ZIF-8 modified by Fe-phenanthroline into Fe-incorporated and N-doped carbon dodecahedron nanoarchitecture(Fe-NCDNA), in which carbon nanosheets are formed in situ as the building blocks with uniform Fe-N-C species decoration. Systematic electrochemical studies demonstrate that the as-synthesized Fe-NCDNA electrocatalyst possesses highly attractive catalytic features toward the ORR in terms of activity and durability in both alkaline and neutral media. The Zn-air battery with the optimal Fe-NCDNA catalyst as the cathode performs impressively, delivering a power density of 184 m W cm^–2 and a specific capacity of 801 m Ah g^–1;thus, it exhibits great competitive advantages over those of the Zn-air devices employing a Pt-based cathode electrocatalyst.

Laminar Forced Convection Heat and Mass Transfer of Humid Air across a Vertical Plate with Condensation

Condensation of humid air along a vertical plate was numerically investigated, with the mathematical model built on the full boundary layer equations and the film-wise condensation assumption. The velocity, heat and mass transfer characteristics at the gas-liquid interface were numerical analyzed and the results indicated that it was not reasonable to neglect the condensate film from the point of its thickness only. The condensate film thickness, interface temperature drop and the interface tangential velocity affect the physical fields weakly. However, the subcooling and the interface normal velocity were important factors to be considered before the simplification was made. For higher wall temperature, the advective mass transfer contributed much to the total mass transfer. Therefore, the boundary conditions were the key to judge the rationality of neglecting the condensate film for numerical solutions. The numerical results were checked by comparing with experiments and correlations.

Effect of agitation on the characteristics of air dense medium fluidization

In order to study the effect of agitation on the characteristics of air dense medium fluidization, we designed and constructed an agitation device. Analyses were then conducted on the fluidization characteristics curves, the bed density stability and the average bubble rise velocity Uaunder different agitation conditions. The results indicated that a lower bed pressure drop(without considering lower gas velocity in a fixed bed stage) and higher minimum fluidized velocity are achieved with increasing agitation speed.The height d(distance between the lower blades and air distribution plate) at which the agitation paddle was located had a considerable effect on the stability of the bed density at 9.36 cm/s < U < 10.70 cm/s. The higher the value of d, the better the stability, and the standard deviation of the bed density fluctuation r dropped to 0.0364 g/cm^3 at the ideal condition of d = 40 mm. The agitation speed also had a significant influence on the fluidization performance, and r was only 0.0286 g/cm^3 at an agitation speed of N = 75 r/min. The average bubble rise velocity decreased significantly with increasing agitation speed under the operating condition of 1.50 cm/s < U–U_(mf)< 3.50 cm/s. This shows that appropriate agitation contributes to a significant improvement in the fluidization quality in a fluidized bed, and enhances the separation performance of a fluidized bed.

Energy Efficiency, Indoor Air Quality and Thermal Comfort Studies at the Faculty of Engineering and Built Environment, University Kebangsaan Malaysia

The study was conducted to identify indoor air quality and the level of thermal comfort in various selected locations in Faculty of Engineering and Built Environment （FKAB）, University Kebangsaan Malaysia （UKM） with built-up area of 250,936 fie. The indoor air quality and thermal comfort were measured at various selected locations by using indoor air quality equipment （Thermal Comfort SERI）. The thermal comfort assessments are based on Malaysian Code of Practice Indoor Air Quality 2005 and Moderate Thermal Environments-Determination of the PMV and PPD indices specification of the condition for thermal comfort （ISO7730：1994） From the data analysis, the FKAB building is considered inadequately vented space. The concentration of CO2 for all sampling area evaluated exceeds the recommended concentration （〉 1000 ppm）. The ventilation system used in FKAB building is designed by delivering fix amount of fresh air into building from external building without consideration on the number of occupants. This common ventilation design will increase the amount of CO2 dramatically all day long and these reflect the inefficiency of energy used. The faculty needs to be equipped with a comprehensive energy management system that can allow detailed documentation of continuous performance of all energy system and consumption in the building.

Numerical simulation study on the thermal environment in heading face

Based on κ-ε turbulence model, the distributions of the velocity field, tempera- ture field, thermal comfort index, PMV-PPD （Predicted Mean Vote-Predicted Percentage Dissatisfied）, and air quality index, mean age of air were obtained of Zhouyuanshan Coal Mine in -650 m level of a heading face by CFD（Computational Fluid Dynamics）software, Airpak 2.0. Moreover, the human thermal comfort and the air quality of the heading face were analyzed with PMV-PPD and mean age of air indices, which received an intuitive visualization and accurate evaluation results. In order to create a safe, comfortable, and economical underground operating environment, a scientific, rational, and comprehensive prediction and evaluation needed to provide a theoretical and technical basis for coal mine ventilation, cooling, heat harm treatment, and prevention. Meanwhile, from the human thermal comfort and air quality to research the underground environment, it embodied the concept of being human oriented.

Impact of human motion on TVOCs inhalation dose under side re-circulated ventilation

The main objectives were to (1) calculate the total volatile organic compounds (TVOCs) inhalation dose, (2) analyze the proportions of human’s inhaled contaminant dose from different sources, and (3) present a newly defined ratio of relative inhalation dose level (RIDL) to assess indoor air quality (IAQ). A user defined function based on CFD (computational fluid dynamics) was developed, which integrated human motion model with TVOCs emission model in a high sidewall air supply ventilation mode. Based on simulation results of 10 cases, it is shown that the spatial concentration distribution of TVOCs is affected by human motion. TVOCs diffusion characteristic of building material is the most effective way to impact the TVOCs inhalation dose. From the RIDL index, case A-2 has the most serious IAQ problem, while case D-1 is of the best IAQ.

Effects of Postharvest Hot Water and Hot Air Treatments on Storage Decay and Quality Traits of Kumquat （Fortunella japonica Lour. Swingle, cv. Ovale） Fruit

Heat treatments such as hot-water dipping （HWD）, hot water rinsing and brushing （HWRB）, and hot air treatment （HAT） have been applied on a wide range of horticultural crops to control postharvest decay and to maintain quality characteristics. In this study we compared the influence of hot-water dipping （HWD） for 2 rain at 50℃and hot air treatment （HAT） at 37 ℃ for 30 hours, on postharvest performance of kumquat （Fortunellajaponica Lour. Swingle, cv. Ovale） fruit. Decay development, transpiration rate （fruit weight loss）, external appearance, and nutritive （sugars and organic acids） and functional properties （ascorbic acid, total phenolic compounds, and total antioxidant activity） were evaluated over 21 days＇ simulated shelf-life at 17 ℃. Untreated fruits were used as control. There was no visible damage to the fruit following HWD or HAT and after storage. However, while HWD and control fruit maintained their fresh appearance during the first 14 days of storage and were rated as fairly fresh after the 21 days, HAT fruits had lost their gloss and no longer appeared fresh. HWD did not affect fruit weight loss while HAT induced significant weight loss with respect to control. HAT did not significantly affect decay incidence after 14 days＇ storage but effectively reduced decay after 21 days＇. HWD notably reduced decay development after 14 and 21 days of storage and proved significantly more effective than HAT. Neither HWD nor HAT significantly affected the nutritive and functional properties of fruit. Thus, present results indicate that while HWD can be applied on kumquats to control postharvest decay without impairing the quality traits, HAT conditions （treatment time and temperature） should be optimized, due to adverse effects to fruit quality.

Novel Air Purification System for Installation in Air Handling Units： Development, Assembly and Experimental Analysis

Nowadays, people pass 90% of their time in closed spaces, therefore, an increasing care in the creation and upkeep of healthier environments as a personal and as professional level become a major issue. The present project has as goal the verification and optimization of the implicit need of an OCRAMclima~ AHU （air handling units） in IAQ （indoor air quality） and its effectiveness in treatment and/or air purification, having as basis the legal national and European requirements for IAQ. This work was based on the study of the state of the art of the techniques in air purification and in the evaluation of their performance, culminating in the production of the prototype OCRAMclima~ NPS （nano purifying system）. The purifying phenomena involved are UVGI （ultraviolet germicidal irradiation） and catalytic ionization of air. The performance test was accomplished in a closed loop circuit, which results, obtained by an independent IAQ analyst, were satisfactory, indicating the viability of application of this system to indoor air disinfection. The outcome revealed that the conjugating of both phenomena, the air sterilizing by UV and catalytic ionization, is efficient when used for air purification, mainly for volatile organic compounds and bioaerosols.

The Structure of a Typical Mei-Yu Front Identified by the Equivalent Temperature

In China's Mainland, the summer monsoon rainy band is referred to as the mei-yu precipitation front, which extends northward from South China to the Yangtze River, Huaihe River, and Yellow River, depending on the season. This paper describes the structure of the mei-yu front associated with a persistent heavy rainfall event that occurred in the summer of 2007. The mei-yu front occurs when the subtropical oceanic warm, moist air mass and the extra tropical continental dry, cold air mass converge on the lee side of the Tibetan Plateau. The authors defined the equivalent temperature using two terms of dry-air temperature and the specific humidity and calculated its horizontal gradient to indicate the mei-yu front. The vertical structure of the mei-yu front and the moist thermal winds surrounding it were examined based on the equivalent temperature.

Development of an Emulator for the Plasma Process Control

This work aims at developing an automatic system for the control of the APS （air plasma spraying） plasma process in which some instability phenomena are present. APS is a versatile technique to produce coatings of powder material at high deposition rates. Using this technique, powder particles are injected into a plasma jet, where they are melted and accelerated towards a substrate. The coating microstructures and properties depend strongly on the characteristics of the plasma jet, which can be controlled by the adjustment of the process parameters. However, the imeractions among the spray variables, render optimization and control of this process are quite complex. Understanding relationships between coating properties and process parameters is mandatory to optimize the process technique and the product quality. We are interested in this work to build an on-line control model for the APS process based on the elements of artificial intelligence and to build an emulator that replicates the dynamic behavior of the process as closely as possible.

Performance and Economic Analysis of Mulberry Paper Handmade Dryer by Using Downdraft Gasifier

The mulberry paper handmade dryer uses downdraft gasifier, which is a continuous hot air dryer. The downdraft gasifier uses charcoal or wood chip as fuel to produce the producer gas for a dryer heat source. Two steps operation of a dryer as follows： The frst was to reduce mulberry paper pulp moisture by an air vacuum pump; the second was a continuous hot air drying process. The optimum condition drying, the capacity of dryer, the fuel consumption, the drying constant （k） and economics analysis were investigated. It was found that the first step could be to reduce mulberry paper pulp moisture content about 25% and the suitable condition drying was 80 ~C drying temperature, 0.04 kg/s air mass flow rate and 0.29 m/min chain conveyor speed, respectively. The capacity of this dryer was 20 sheets per hour. The quality of mulberry paper product was very good （based on the standard of mulberry paper community 41/2546） and the fuel consumption rate was 5 kg/h （charcoal）. The drying constant was about 0.532933-0.541367 min~ and the drying constant was a function of drying temperature （T）, air mass flow rate （F） and conveyor speed （10 as equation of k（T, F, V） = 0.567494 ＋ 0.000422T- 1.40588F- 0.000205 V （R2 = 0.9254） and the breakeven point of dryer was 0.79 years.

Perceived Indoor Discomfort, Performance and Productivity

Even all indoor environmental standards are met the users are usually not satisfied and perceived discomfort is occurred in the smart office buildings. The most frequently cause of discomfort in smart buildings is overrun of intelligence. There are physical and psychological factors that influenced building users＇ comfort. An indoor air quality seems to be one of the main problems of smart office buildings. In Slovakia the office buildings relating to indoor environment European standard are mostly evaluated as the non-low polluting buildings. The pollution from building as well as the pollution from occupancy and using was respected. The odor intensity and indoor air acceptability were assessed by a sensory panel. The concentrations of total volatile organic compounds and carbon dioxide were measured. The odors from building materials studied under different air change rate are presented in this paper. The case study of indoor air acceptability concerning to indoor odors under occupancy and its affect on perceived air quality influenced by air change rate are also presented in this paper.

Drying Characteristic of Anchovy Fish

This paper focuses on the drying characteristic of anchovy fish （Anchovia engraulidae）. It is necessary to understand the drying behavior, quality of the products and time required to optimize the energy consumption of the process. The optimum velocity and temperature of drying air for good quality dried anchovy fish was determined. In average, the fish are 7 cm in length and 3.0-3.5 g in mass. Although some research on fish drying has been done, the study of drying of anchovy fish and its characteristic has not been well reported. The fish to be dried were arranged on 15 × 15 cm2 tray in the drying chamber of 17 × 30 cm2. The hot air of 40 -70 ℃ was delivered parallel to the tray with the velocity of 0.6 and 0.9 m s-1. It is found that thermal conductivity （k） and specific heat （cp） of anchovy fish are function of the moisture content （MC）. The higher moisture content results in higher thermal conductivity and specific heat. Critical water content is also found in this experiment as well as the optimum drying condition. Drying rate period of anchovy fish will change from the constant drying rate period to the falling drying rate period when critical moisture content is about 48.8%-50.3% （wet basis）. At these experiments, there is no case-hardening, even at temperature of 70 ℃. To achieve the optimum result, the drying process should be implemented in three steps, drying process at 70 ℃ for 150 min followed by drying at 50℃ for 100 min, and finally drying at 40℃ till achieving equilibrium moisture content. This research will contribute to improvement of drying method to achieve good quality of dried fish.

Engineering Solutions towards Cost-Effective Sustainable Environment and Living

One important area where the development of economically viable products can improve the quality and comfort of human existence is natural ventilation inside a building. Despite the wide distribution of air pollutant sources, the concentration of indoor pollutants may be the dominant risk factor in relation to personal exposure, as most people spend an average of 87% and 6% of their time within enclosed rooms and vehicles, respectively. Under these circumstances, wind driven rotating ventilators, which use natural energy and are cheap to manufacture, install and maintain, can become very effective non-polluting means of alleviating the problems within enclosed spaces. The author has been pioneering design and performance studies of environment friendly products such as the rooftop ventilator for over a decade at the University of New South Wales in Australia. The purpose of this paper is to detail the basic working principles of this ventilator and the series of detailed experimental and numerical investigations that has been performed in the optimization of the rooftop ventilator in terms of performance with higher air mass extraction rate and improved safety in operation has been achieved. Findings from these studies have been incorporated in the design of ventilators that are now commercially produced and marketed throughout the world by CSR Edmonds Pry Ltd of Australia. The conduct and outcomes of these works form the basis of this keynote paper.

Performance and Effectiveness of Portable Air Cleaners in an Office Room： An Experimental Study

Nowadays, many people work in an office environment. Air pollutants, including particles and gases, are generated by humans and by different devices that are used in offices. Pollutants can also enter an office room with the air supplied from outdoors. It has been established that air pollutants have adverse health effects on human body. Air cleaning devices are commonly marketed as being beneficial for the health by removing air pollutants and consequently improving indoor air quality. The performance of five air cleaning technologies was tested in order to determine the generation of ozone and particles in an office room. The particle removal effectiveness of the technologies was also determined in order to clarify their ability to remove UFPs （ultrafine particles） in the office room. The tested five air cleaning technologies are non-thermal plasma, corona discharge ionizer, portable air purifier, electrostatic fibrous filter and three-dimensional fibrous filter. The interior surfaces of the office room emit low levels of volatile organic compounds, since the office room has not been refurbished for about two decades. The results showed that the particle removal effectiveness of the technologies was ranged between 0.2 and 0.45 for the office room. The three technologies using/generating ozone significantly increased the ozone level in the office room. However, no increase of the UFP concentration was detected.

Pt/Zn heterostructure as efficient air-electrocatalyst for long-life neutral Zn-air batteries

Neutral Zn-air batteries(ZABs) have attracted much attention due to the enhanced lifespan and stability.However, their development is suppressed by the poor catalytic properties of the air-electrocatalysts for oxygen reduction reaction(ORR) and oxygen evolution reaction(OER). Hence,the exploration of highly efficient electrocatalysts for neutral ZABs is critical. Herein, we designed an economical heterostructure of Pt nanoparticle-modified Zn nanoplates(Pt/Zn NPs). Compared with commercial Pt/C electrocatalyst, our Pt/Zn heterostructure exhibits comparable catalytic properties and ultrahigh stability in neutral media. The heterostructure can reduce the dosage of Pt and offer sufficient active sites,resulting in enhanced catalytic properties for ORR/OER in neutral media. When applied to neutral ZABs as air cathode,our heterostructure exhibits a high power density of 45 mW cm^(-2) and excellent stability of more than 850 cycles with negligible decay, making it the most efficient and robust one in neutral electrolyte. This approach opens a new avenue to strategically design catalysts with high activity for neutral ZABs, rendering them potential in portable and wearable electronic devices.

Oxygen vacancies effects on phase diagram of epitaxial La1-xSrxMnO3 thin films

We investigated the effects of oxygen vacancies on the structural, magnetic, and transport properties of Lal-xSrxMnO3 （x=0.1, 0.2, 0.33, 0.4, and 0.5） grown around a critical point （without/with oxygen vacancies） under low oxygen pressure （10 Pa） and high oxygen pressure （40 Pa）. We found that all films exhibit ferromagnetic behavior below the magnetic critical temperature, and that the films grown under low oxygen pressures have degraded magnetic properties with lower Curie temperatures and smaller magnetic moments. These results show that in epitaxial La1-xSrxMnO3 thin films, the magnetic and transport properties are very sensitive to doping concentration and oxygen vacancies. Phase diagrams of the films based on the doping concentration and oxygen vacancies were plotted and discussed.