This study investigated the effects of temperature and humidity on the photocatalytic oxidation of volatile organic compound (VOCs) over titanium dioxide. Benzene, methyl tert-butyl ether (MTBE), perchloroethylene (PCE), and toluene were selected to investigate the influences of temperature and humidity on photocatalytic conversion. Among these four VOCs, benzene and MTBE were selected for the investigation of reaction pathways and kinetics. This work employed a self-designed annular packed-bed photocatalytic reactor to determine the conversion and reaction rates during photocatalytic degradation of VOCs. Degussa P-25 TiO2 was used as the photocatalyst and a 15 W near-UV lamp (350 nm) served as the light source. Benzene conversions increased with temperature below 160 ºC, but decreased above 160 ºC. Moreover, the conversions of MTBE increased with temperature from 30 to 120 ºC, and the thermocatalytic reaction began above 120 ºC. The conversions of PCE decreased as the temperature increased from 120 to 200 ºC. Toluene conversions almost remained constant at 100~200 ºC. Based on the gas-solid catalytic reaction theory, raising the reaction temperature could promote the chemical reaction rate and reduce reactant adsorption on TiO2 surfaces. The overall reaction rate increased with temperature, indicating that the reduction of reactant adsorption did not affect the overall reaction, and thus the chemical reaction was the rate-limiting step. As the chemical reaction rate gradually increased and the reactant adsorption decreased with temperature, the rate-limiting step could shift from the chemical reaction to the reactant adsorption, while the overall reaction rate decreased with temperature. Additionally, the competitive adsorption between VOCs and water for the active sites on TiO2 resulted in VOCs influent concentration and humidity promoting or inhibiting the reaction rate. The mineralization of benzene and the selectivity of CO and CO2 were not obviously affected under various temperatures, humidities, and influent benzene concentrations. The benzene mineralization ratios ranged from 0.85 to 1.0, to which CO and CO2 contributed approximately 5~20% and 80~95%, respectively. Temperature and humidity variation did not influence the photocatalytic reaction pathway of benzene. Acetone (AC) and tert-butyl alcohol (TBA) were two major organic products for the photocatalysis of MTBE. The addition of water transferred the reaction pathway from producing AC to TBA, while the temperature increase transferred the reaction pathway from producing TBA to AC. A modified bimolecule Langmuir-Hinshelwood kinetic model was developed to simulate the temperature and humidity related promotion and inhibition of the photocatalysis of benzene and MTBE. The competitive adsorption of VOCs and water on the active sites resulted in VOCs influent concentration and humidity promoting or inhibiting the reaction. The reaction rate constant increased with temperature while the adsorption equilibrium constants decreased, confirming that increasing reaction temperature enhanced the chemical reaction, but reduced the adsorption of VOCs and water. Furthermore, the correlation developed here was also used for determining the apparent activation energy of photocatalytic oxidation of VOCs and the adsorption enthalpies of benzene, MTBE, water vapor, and oxygen.

Thin cirrus clouds play an important radiative role in the earth's atmosphere and climate system, yet are one of the least understood components of the climate system. With the use of data from Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO), thin cirrus and thick cloud distributions in the tropics are analyzed at 121, 100, and 82 hPa. Observations obtained between December 2006 and November 2007 show that thin cirrus between 30°N and 30°S occur in close proximity to regions of intense convection and are positively correlated with low values of outgoing longwave radiation (OLR). In conjunction with the CALIPSO data, water vapor data from the Earth Observing System (EOS) Microwave Limb Sounder (MLS), OLR data provided by the NOAA/OAR/ESRL PSD, Boulder, Colorado, USA, from their Web site at http://www.cdc.noaa.gov/, and linearly interpolated NCEP reanalysis temperature data were used. These data were used to examine how thick and thin cirrus cloud fractions at 121-hPa and 100-hPa are related to relative humidity with respect to ice (RHI), temperature, and OLR. Our observations show that both RHI and convection play important roles in the development and maintenance of thick and thin cirrus clouds at the pressure levels of interest. The highest fractions of clouds are almost always seen within OLR values representative of convection and at relatively high values of RHI. However, when peaks in cloud fraction are found above the convective threshold, higher RHI values are needed than are needed when convection is responsible for the formation and maintenance of these clouds.

The development of a control-oriented dynamic relative humidity model for a polymer electrolyte membrane (PEM) fuel cell stack is presented. This model is integrated with a first law based thermal model, which tracks energy flow within four defined control volumes in the fuel cell; the cathode channel, anode channel, coolant channel, and fuel cell stack body. Energy and mass conservation equations are developed for each control volume. On top of mass conservation, electro-drag and osmosis models were also implemented within the model to account for the major modes of vapor transfer through the membrane between the anode and cathode. Requisite alterations to the thermal model as well as mass flow rate calculations are also discussed. Initially, the model utilized a single lumped control volume for the calculation of all values each channel (anode and cathode). This lumped value method is computationally inexpensive, and makes the model optimal for control design. However, investigation of the mass-based Biot number showed the need for greater granularity along the length of the channels to properly capture the relative humidity dynamics. In order to improve the resolution of the model, while still minimizing the computation expense, the model was subdivided into a series of lumped value models. The cathode channel was the point of focus as it is the major concern from a controls perspective. This method captures the proper trends found in far more complex CFD models, while still maintaining a quick calculation time. Different levels are subdivision (3 and 6 submodels) are investigated, and the differences discussed. Particularly, temperature range, relative humidity range, the effect on the modeled voltage, and calculation time are compared. This control-oriented model is low order and based on lumped parameters, which makes the computational expense low. Formulation of this model enables the development of control algorithms to achieve optimal thermal and water management. / text

No description available.

No description available.

Phytophagous insects and plants comprise one half of all macroscopic organisms on Earth, and understanding plant-insect interactions has been a long-standing focus in ecological and evolutionary biology. A key challenge has been determining the factors that affect how insects distribute among plants. While ditrophic and tritrophic interactions are well known and enormously important, the biophysical context in which these interactions occur is largely unexplored. This dissertation examines how a plant's physical environment affects insect performance on, and preference for, its leaves.An insect's primary physiological challenges are staying within an appropriate temperature range and retaining sufficient water. These problems are exacerbated during the egg stage. Eggs have comparatively enormous ratios of surface area to volume, and their temperature is determined largely by where they are laid. Because they are small, eggs are nearly always immersed within their plant's boundary layer, a thin layer of still air that resists heat and moisture transfer between the plant and its surroundings. Almost no work has documented the microclimate to which insects are exposed in a plant's boundary layer, which likely differs substantially both from the ambient macroclimate, and from leaf to leaf.Because a female controls the location in which her eggs must develop, her choice of oviposition site may profoundly influence the success of her offspring. In this dissertation I examine how site-specific environmental variables, including microclimate, predation, and leaf nutrition, drive female oviposition preference and offspring performance in the hawkmoth, Manduca sexta L. (Lepidoptera: Sphingidae). I measure how leaves of M. sexta's primary host plants in the southwestern USA modify the temperature and humidity experienced by eggs, and how these leaf microclimates affect the performance of eggs and larvae. I then test whether this species' oviposition-site choices correlate with offspring performance with regard to microclimate, predation risk, and leaf nutrition. This dissertation is unique in focusing on the relatively unstudied biophysical context in which plant-insect interactions occur. Additionally, it is the first work that compares, together in a single study, the effects of varying multiple factors related to oviposition-site choice across all life history stages in a single model system.

Humidity sensors are one of the most widely used sensors in commercial and industrial applications for environmental monitoring and controlling. Although related technology have been studied intensively, humidity sensing in harsh environments still remains a challenge. The inability of current humidity sensors to operate in high temperature environments is generally due to the degradation of the sensing films caused by high temperature, high humidity level, and/or contamination. Our goal is the design and fabrication of a humidity sensor that is capable of working under high temperatures and in a condensing environment. The targeted application of this sensor is in the polymer electrolyte membrane (PEM) fuel cell, where humidity control is crucial for performance optimization. In this work, ordered macroporous silicon is thoroughly studied as a humidity sensing layer. In addition to the advantages of traditional porous silicon for gas sensing (high resistance to high temperature and good compatibility with current IC fabrication process), the ordered macroporous silicon used in these experiment has uniform pore size, pore shape and distribution. All the vertical aligned pores can be opened to the environment at both ends, which can significantly increase the efficiency of gas diffusion and adsorption. Moreover, this special structure opens the door to uniform surface modifications for sensing enhancement. Both ordered macroporous silicon based heterostructure and self-supporting membrane are fabricated and investigated as a humidity sensor. Heterostructure sensors with different thin film surface coatings including bare Si, thermally grown SiO2, atom layer deposited ZnO, HfO2, and Ta2O5 are characterized. Post micro-fabrication is achieved on this ordered porous structure without affecting the material and its sensing properties. It has been proven that the ordered macroporous silicon with Ta2O5 surface coating shows the best sensing property due to its ultra-hydrophilic surface. The sensor shows high sensitivity, fast response times, small hysteresis, and extraordinary stability and repeatability under high temperatures and in condensing environment. It demonstrates great potential and advantages over existing commercial humidity sensors in the fuel cell application field. In addition to ordered macroporous silicon, well aligned 1D ZnO nanorods/nanowires -another widely used nanostructure in gas sensing- is also investigated as humidity sensing materials. Both vertically and laterally aligned nanorods/nanowires are fabricated and tested against humidity changes. The sensors shows increasing resistance to increasing relative humidity, which is contrary to most published works so far. Possible mechanisms have been proposed in this thesis and future work has been suggested for further study. To the best of our knowledge, this work is the first to use ordered macroporous silicon and well aligned 1D ZnO nanorods/nanowires for humidity sensing.

Tiriant didėjančių temperatūrų ir drėgmės deficito poveikį sėjamųjų žirnių biometriniams ir biocheminiams rodikliams, bandymai atlikti LSDI Augalų fiziologijos laboratorijos fitotroniniame komplekse 2009 metais. Tirta didėjančių temperatūrų ir drėgmės deficito įtaka sėjamųjų žirnių (Pusum sativum L.) 'Gloriosa' antžeminės dalies augimui, žaliųjų bei sausųjų medžiagų kaupimuisi antžeminėje dalyje, asimiliaciniam lapų plotui ir fotosintetinių pigmentų kiekiui. Atlikus tyrimus nustatyta, kad, didėjant temperatūrai ir mažėjant substrato drėgmei chlorofilų a ir b bei karoteno kiekis sėjamųjų žirnių daiguose, didėja. Iš tyrimų duomenų matyti, kad didžiausias sausųjų medžiagų kiekis buvo daiguose, kurie augo normalaus drėgnio (40 - 45%) substrate, aukštesnėje - 25/18 °C temperatūroje. Sėjamųjų žirnių didžiausias daigų lapų plotas buvo prie žemesnės temperatūros ir normalaus substrato drėgnio (40 - 45%). Aukščiausi daigai buvo normalaus drėgnio (40 - 45%) substrate ir prie - 25/18 °C temperatūros. Tyrimai parodė, kad kompleksinis drėgnio ir aukštos temperatūros poveikis skatina žirnių daigų augimą. Taip pat iš duomenų matosi, kad normalus (40 - 45%) substrato drėgnis ir aukštesnė - 25/18 °C temperatūra skatina asimiliacinį žirnių daigų lapų plotą. / A study of rising temperatures and water deficit effects on pea biometric and biochemical characteristics was conducted at LSDI. It was accomplished at Plant Physiology Laboratory fitotronical complex in 2009. The research was made on the influence of rising temperatures and water deficit on pea (Pisum sativum L.) 'Glorioso' canopy growth, green and dry matter accumulation in terrestrial, assimilated leaf area and photosynthetic pigment content. The investigation showed that with increasing temperature and decreasing the substrate moisture of chlorophylls a and b and carotene content of pea shoots have been rising. The survey data shows that the highest dry material concentrations was of the shoots, which grew at normal humidity (40 - 45%) substrate and higher temperature - 25/18 ° C. The highest pea shoots leaf area was lower at normal temperature and substrate moisture (40 - 45%). Tallest plants were normal humidity (40 - 45%) and the substrate - 25/18 ° C temperature. Studies have shown that a complex of high humidity and temperature on pea plants promote growth. Also the data shows that normal (40 - 45%) substrate moisture content and higher - 25/18 ° C temperature promotes assimilation of pea sprouts leaves area.

Informacijos šaltinių analizėje apžvelgti energetiniai augalai, jų fizinės – mechaninės savybės, nuėmimo bei ruošimo kurui technologijos. Apžvelgtos energetiniams augalams tinkamos ir skirtos saugyklos . Eksperimentiniais tyrimais nustatytos pagrindinės gluosnių stiebų pjaustinio biometrinės ir fizinės – mechaninės savybės: trinties savybės ir birumo kampai. Nustatyti pjaustinio laikymo ir džiovinimo technologiniai parametrai. Ištyrus trinties savybes nustatyta, kad gluosnių pjaustiniui slystant plastmasiniu paviršiumi trinties koeficientas yra mažesnis nei slystant metaliniu paviršiumi. Įvertinti pjaustinio laikymo ir džiovinimo parametrai. Nustatyta, kad pjaustinį neventiliuojamoje saugykloje kaista ir supelija. Nustatyta, kad 650±15 m3/(th) oro srautas yra per mažas, nes taip pat prasidėjo pjaustinio gedimas, tai rodo, kad šis srautas yra per silpnas, jis neužkerta kelio pelėsių atsiradimui. Todėl tikslinga naudoti 1300±20 m3/(th) ir didesnį oro srautą. Pasiūlyta saugykla saugoti 3 mėnesių kuro atsargas, kuriomis šildomas 800 m2 ploto gyvenamasis namas (saugykla bus pildoma 3 kartus per šildymo sezoną). / This work consists of 58 pages including 25th picture and 13 tables. There are 23 sources in the information sources‘ list. The work was begun 01 09 2007 and finished 19 05 2009. In the analysis of information sources the energetic plants were overlooked – their physical-mechanical characteristics, gathering and preparing for using as a fuel technologies. Also stores suitable and designed for energetic plants were overlooked. The basic biometric and physical-mechanical characteristics of willow stem chaff like frictional attributes and angle of powderiness were observed by experimental investigation. Technological parameters of chaffs‘ storage and desiccation were appointed. It was appointed while investigating that friction coefficient is lower when willow chaff is sliding through plastic surface than through metal surface. Parameters of chaffs‘ storage and desiccation were evaluated. It was appointed that chaff heats up and gets musty in the unventilated stores. 650±15 m3/(th) windblast is too weak as it also caused spoilage of chaff. It does not prevent uprise of must. It is purposeful to use 1300±20 m3/(th) and higher windblast for ventilation. The store for holding fuel resources for 800 m2 dwelling-house during three months was offered. (The store will be supported three times during the heating season).

Magistro darbe atliekama medienos tūrio nustatymo svėrimo būdu galimybių analizė. Darbo objektas – Apvalioji ir smulkintoji mediena naudojama medienos drožlių plokščių gamybai. Darbo tikslas - Ištirti apvaliosios ir smulkintos medienos, skirtos medžio drožlių plokštės gamybai, tankio kitimo dėsningumus ir jos svorio konvertavimo į tūrį ypatumus. Darbo metodai - Empirinio tyrimo metodas paremtas duomenų rinkimu medieną sveriant, atrenkant mėginius ir juos džiovinant. Kiekybinis palyginimas - statistinis duomenų apdorojimas paremtas dispersine ir regresine analize ir taikant koreliacinius ryšius. Visą empirinę medžiagą sudarė 180 medvežių imtis su spygliuočių, lapuočių ir smulkintoji mediena. Tiriama medienos tankio ir drėgnio koreliaciniai ryšiai, taip pat šių parametrų kintamumas nuo medžių rūšies, meteorologinių sąlygų: juos kertant ir sandėliuojant. Darbo rezultatai. Nustatyta, kad didžiausią įtaką medienos tankiui turi medienos drėgnis, o didžiausia drėgnos medienos masė yra žiemą. Pavasarį medienos masė mažėjo, o lengviausia buvo vasarą. Didėjant medienos santykiniam drėgniui, medienos tankis didėja nepriklausomai nuo medžių rūšies, tai rodo, kad medienos drėgnis ir jo kintamumas priklauso nuo metų laiko. Tiek lapuočių, tiek spygliuočių medienos masės priklausomybės nuo santykinio drėgnio kreivė žiemos metu yra aukščiausia, lyginat su pavasario ir vasaros kreivėmis. Tai dar kartą įrodo, kad mediena drėgniausia žiemos metu. Nustatytas drėgnio... [toliau žr. visą tekstą] / In this Master's paper an analysis is carried out to calculate the probability of estimating the volume of timber using the method of weighing. Work -study : Logs and flaked wood used for producing wood cutting panelling The aim of the work: Analysing the changes in thickness of logs and flaked wood used for producing wood cutting panelling and converting its weight into bulk. Methods of work: Empiric method based on weighing the timber, sorting out the samples and drying them. Quantitative analysis - processing the statistic data based on dispersive and regressive analysis and using correlation relations. The empiric analysis covered 180 trucks of softwood, deciduous wood and cutting.The correlation between the thickness and the humidity has been analysed. It has been also analysed how the thickness and humidity change in different species of trees, meteorological conditions, cutting down the trees and storing them. The results of the work: It has been decided that the greatest influence on the thickness of the wood has the density of the wood. The greater the relative density of the timber, the bigger the thickness of the timber. And it doesn't depend on the kind of the wood. It shows that the thickness of the wood and its changing depends on the season of the year. The curve of relative density in winter is the highest if ompared with the one in spring or in winter. The rate of the variation of density has been fixed from 11,5 to 32,2 %. As it is seen the range was great... [to full text]