Genetic Control of Air-Dried Wood Density, Mechanical Properties and Its Implication for Veneer Timber Breeding of New Triploid Clones in Populus tomentosa Carr

The wood samples of 9 triploid clones of Populus tomentosa Carr. taken from a 9 year old clonal test site were analyzed in order to investigate the genetic variation of wood properties, including air dried wood density and some mechanical properties. The results showed that significant or extremely significant difference in air dried wood density and the mechanical properties existed among the clones, this means these wood properties were under moderate or strong genetic controls and could be improved by genetic manipulations. The radial and vertical variation patterns of air dried wood density were also studied and the results were found to coordinate with other previous research results. The vertical variation patterns of most mechanical properties within the individual tree also conformed to the general wood theories except the modulus of elasticity and cross section hardness. Among the mechanical properties, modulus of elasticity (MOE) and tangent section hardness were under strong genetic control, with the clonal repeatabilities being 0 90 and 0 80, respectively. However, the clonal repeatabilities of other mechanical properties under study were a little lower than above two indexes. Genetic correlation analysis indicated that super clonal selection and breeding for veneer timber could be realized through indirect selection of wood density and form indexes.

Liquid penetration of freeze-drying and air-drying wood of plantation Chinese fir

A comparative study was conducted on liquid penetration of the freeze-drying and air-drying sapwood and heartwood lumber of plantation Chinese fir （Cunninghamia lanceolata）. The maximum amount of dyeing solution uptake by the capillary rise method was used to evaluate the liquid penetration properties of the treated wood. The pit aspiration ratio was determined by semithin section method. Changes in wood microstructure were investigated using scanning electron microscopy. The results showed that compared with air drying, the freeze drying had a significant effect on liquid penetration of sapwood and heartwood of Chinese fir. The liquid penetration of sapwood is significantly higher than that of the heartwood for both drying treatments. Low pit aspiration ratio and cracks of pits membrane of some bordered pits are the main reasons for increasing liquid penetration after freeze drying treatment.

Impact of Mid-and Upper-Level Dry Air on Tropical Cyclone Genesis and Intensification:A Modeling Study of Durian(2001)

The impact of mid-and upper-level dry air,represented by low relative humidity(RH)values,on the genesis of tropical cyclone(TC)Durian(2001)in the South China Sea was investigated by a series of numerical experiments using the Weather Research and Forecasting model.The mid-level RH was lowered in different regions relative to TC Durian(2001)’s genesis location.Results suggest that the location of dry air was important to Durian(2001)’s genesis and intensification.The rapid development of the TC was accompanied by sustained near-saturated mid-and upper-level air,whereas low humidity decelerated its development.Water vapor budget analysis showed that moisture at mid and upper levels was mainly supplied by the vertical convergence of moisture flux and the divergence terms,and consumed by the condensation process.The horizontal convergence of moisture flux term supplied moisture in the air moistening process but consumed moisture in the air drying process.With a dryer mid-and upper-level environment,convective and stratiform precipitation were both inhibited.The upward mass fluxes and the diabatic heating rates associated with these two precipitation types were also suppressed.Generally,convection played the dominant role,since the impact of the stratiform process on vertical mass transportation and diabatic heating was much weaker.The vorticity budget showed that the negative vorticity convergence term,which was closely related to the inhibited convection,caused the vorticity to decrease above the lower troposphere in a dryer environment.The negative vorticity tendency is suggested to slow down the vertical coherence and the development rate of TCs.

External Heat Transfer in Moist Air and Superheated Steam for Softwood Drying

In kiln drying of softwood timber, external heat and moisture mass transfercoefficients are important in defining boundary temperature and moisture content at the woodsurface. In addition, superheated steam drying of wood is a promising technology but this has notbeen widely accepted commercially, partially due to the lack of understanding of the dryingphenomena occurred during drying. In this work, experimental investigation was performed to quantifythe heat transfer between wood surface and surrounding moist air or superheated steam. In theexperiment, saturated radiata pine sapwood samples were dried using dry-bulb/wet-bulb temperaturesof 60℃/50℃, 90℃/60℃, 120℃/70℃, 140℃/90℃, 160℃/90℃, 140℃/100℃ and 160℃/100℃. The lasttwo schedules were for superheated steam drying as the wet-bulb temperature was set at 100℃. Thecirculation velocity over the board surface was controlled at 4.2m·s^(-1). Two additional runs(90℃/60℃) using air velocities of 2.4 m·s^(-1) and 4.8 m·s^(-1) were performed to check theeffect of the circulation velocity. During drying, sample weight and temperatures at wood surfaceand different depths were continuously measured. Prom these measurements, changes in woodtemperature and moisture content were calculated and external heat-transfer coefficient wasdetermined for both the moist air and the superheated steam drying.

Analysis and Modeling of Wangqing Oil Shale Drying Characteristics in a Novel Fluidized Bed Dryer with Asynchronous Rotating Air Distributor

In order to replace the conventional distributor, a novel asynchronous rotating air distributor, which can optimize the drying ability of fluidized bed and strengthen the drying performance of oil shale particles, is creatively designed in this study. The rotating speed of the asynchronous rotating air distributor with an embedded center disk and an encircling disk is regulated to achieve the different air supply conditions. The impacts of different drying conditions on the drying characteristic of Wangqing oil shale particles are studied with the help of electronic scales. The dynamics of experimental data is analyzed with 9 common drying models. The results indicate that the particles distribution in fluidized bed can be improved and the drying time can be reduced by decreasing the rotating speed of the embedded center disk and increasing the rotating speed of the encircling disk. The drying process of oil shale particles involves a rising drying rate period, a constant drying rate period and a falling drying rate period. Regulating the air distributor rotating speed reasonably will accelerate the shift of particles from the rising drying rate period to the falling drying rate period directly. The two-term model fits properly the oil shale particles drying simulation among 9 drying models at different air supply conditions. Yet the air absorbed in the particles' pores is diffused along with the moisture evaporation, and a small amount of moisture remains on the wall of fluidized bed in each experiment, thus, the values of drying simulation are less than the experimental values.

Effect of different drying methods on the taste and volatile compounds,sensory characteristics of Takifugu obscurus

Pufferfish is prone to deterioration due to abundant nutrients and high moisture content.Drying technology can extend the shelf life and enhance the flavor quality of aquatic products.The study investigated the effect of hot air drying(HAD),microwave vacuum drying(MVD)and hot air assisted radio frequency drying(HARFD)on the taste and volatile profiles of Takifugu obscurus.Different drying methods had significant influence on the color,rehydration,5’-nucleotides,free amino acids and volatile components(P<0.05).The results showed that HAD and HARFD could promote the flavor of T.obscurus by producing higher equivalent umami concentration(EUC)values,which were about two times of MVD group,and more pronounced pleasant odor according to sensory analysis.HAD is more appropriate for industrial application than HARFD and MVD considering the economic benefits.This study could provide a reference for the industrial application of drying T.obscurus.

MECHANISM AND APPLICATION OF COAL DRY BENEFICIATION WITH AIR-DENSE MEDIUM FLUIDIZED BED

The mechanism of beneficiation with air dense fluidized bed has been theoretically studied in the paper. Focusing attention on the misplacing resources in separation process, the misplacing effects are divided into two parts called respectively as misplacing effect of viscosity and misplacing effect of motion. The proposed separation theory can reasonably explain the results of separation in different fluidization states. Experimental results in pilot and commercial plants showed that the air dense medium fluidized bed is a high efficiency dry cleaning technique. The dynamic stability of fluidized bed density is directly affected by the variation of fine coal content in fluidized bed and can be controlled in expected range through measurement of fluidized bed density and adjusting of split flow rate. With air dense medium fluidized bed, various coals of size 50—6 mm can be efficiently beneficiated. The separation density can be adjusted between 1.2—2.2 g/cm 3, and the probable error E p value is about 0.06.

EFFECT OF DRY COLD AIR ACTIVITY ON THE OFFSHORE RAPID INTENSIFICATION OF SUPER TYPHOON SAOMAI(2006): A NUMERICAL SIMULATION RESEARCH

Employing the mesoscale WRF(Weather Research and Forecast) model, Super Typhoon Saomai(2006) is simulated. The variation of track and intensity and its offshore rapid intensification process are well demonstrated by the model, and the temperature and humidity patterns associated with the dry cold air activity and their impact on and mechanism of the offshore rapid intensification of Saomai are mainly studied in this paper. The results indicate that high-resolution water vapor imagery can visually reveal the development, evolution, interaction as well as the mutual complementation of the dry cold air activity accompanied with the development of Saomai. The offshore rapid intensification phenomenon of Saomai is closely related to the dry cold air which originates from the upper- and mid-troposphere. Besides, the dry cold air from the upper troposphere is stronger than that from the mid-troposphere.Saomai intensifies as the dry cold air from the northwest moves toward its circulation but weakens when the dry cold air from the southwest is drawn into the storm. Dry cold airflows and their cold advection effect caused by the downward motion across the isentropic surface are favorable to the development of Saomai. The dry cold air always moves along an isentropic surface from the upper troposphere to the mid-troposphere around the typhoon circulation and contributes to Saomai's abrupt intensity change.

Artificial neural network techniques to predict the moisture ratio content during hot air drying and vacuum drying of Radix isatidis extract

Background:To predict the moisture ratio of Radix isatidis extract during drying.Methods:Artificial neural networks were designed using the MATLAB neural network toolbox to produce a moisture ratio prediction model of Radix isatidis extract during hot air drying and vacuum drying,where regression values and mean squared error were used as evaluation indexes to optimize the number of hidden layer nodes and determine the topological structure of artificial neural networks model.In addition,the drying curves for the different drying parameters were analyzed.Results:The optimal topological structure of the moisture ratio prediction model for hot air drying and vacuum drying of Radix isatidis extract were“4-9-1”and“5-9-1”respectively,and the regression values between the predicted value and the experimental value is close to 1.This indicates that it has a high prediction accuracy.The moisture ratio gradually decreases with an increase in the drying time,reducing the loading,initial moisture content,increasing the temperature,and pressure can shorten the drying time and improve the drying efficiency.Conclusion:Artificial neural networks technology has the advantages of rapid and accurate prediction,and can provide a theoretical basis and technical support for online prediction during the drying process of the extract.

Effects of Chemical Osmotic Pretreatment on Drying Characteristics and Quality of Blueberry under Hot Air Drying

In order to study the effects of chemical osmotic pretreatment on the characteristics and quality of blueberry under hot air drying,fresh blueberries were pretreated with 2.5 g/100 mL K2CO3+0.6 g/100 mL olive oil,and 5.0 g/100 mL K2CO3+0.6 g/100 mL olive oil at(45±0.5)℃,respectively.The changes of water content,rehydration,hardness,microstructure,color difference,active ingredient anthocyanin,total phenol and DPPH radical scavenging capacity of dried blueberries in different treatment groups under hot air drying were compared and analyzed.The results showed that the dehydration rates of blueberries vary greatly according to the type of pretreatments when the samples were dried to the same water content with hot air.Specifically,the dehydration rate of dried blueberries pretreated by 5.0%K2CO3 solution was the highest,followed by 2.5%K2CO3 osmotic pretreatment and lastly the control group;the corresponding dehydration time was 10,14 and 20h,respectively.The physical qualities of dried blueberries,involving the browning degree,color difference,rehydration and microstructure,were significantly different between the chemical osmotic pretreatment group and the control group(P<0.05).The chemical osmotic pretreatment of K2CO3 solution increased the dehydration rate of the samples,shortened the drying time and maintained the quality of blueberries dried with hot air.There was no significant difference between the physical quality of dried blueberries pretreated by 2.5%and 5.0%K2CO3 solution(P>0.05),whereas there was significant difference in drying time and nutrient quality which is characterized by total phenols,anthocyanins,DPPH radical scavenging rate,soluble total sugar(P<0.05).Conclusion:5.0%K2CO3 osmotic pretreatment combining with hot air drying can improve the dehydration rate,shorten the drying time and maintain the physical and nutritional quality.

DRY CLEANING OF COAL WITH AIR DENSE MEDIUM FLUIDIZED BED

This paper deals with the experimental study of dry cleaning of coal with air dense medium fluidized bed. This technique opens up an efficient way of coal separation for vast areas in the country where water resources are in short supply or coals tend to slime seriously in wet process. Tests show that it can separate any kind of coal (6--50mm) efficiently. The probable error E, can reach 0.05--0.08. The separating density can be adjusted in the range of 1.0--2.0 g/cm^3. This technique brings about enormous economic benifits.

Hot Air Drying and Quality of Red and White Varieties of Onion (Allium cepa)

This study was undertaken to investigate the drying characteristics of red and white varieties of onion (Allium cepa) in a convective dryer. The drying characteristics of onion slices were examined at air temperatures of 50℃, 60℃ and 70℃ and sample thicknesses of 2 mm. During the drying experiments, air velocity was held stable at 0.9 m/s. The effects of air temperature on the drying characteristics and quality parameters such as vitamins C and D, macro minerals (Mg, Na, P, Ca and K), non-enzymatic browning and thiolsulphinate of the dried onion slices were determined. For each of the plots of the drying curves from the mechanical drying tests, there was an absence of or just a very brief appearance of a constant rate period because onions are hygroscopic and hygroscopic foods tending to quickly enter the falling rate period;drying time decreased considerably with increased temperature. The time required to reduce the moisture content to any given value was dependent on the drying conditions, being the longest at an air temperature of 50℃, 0.9 m/s and the shortest at an air temperature of 70℃ and air velocity of 0.9 m/s. The loss of vitamin C, which is a thermo-sensitive compound, was the least at an air temperature of 50℃.

Characteristics of Dry Cold Air Intrusion in a Typical Strong Storm

Taking a typical strong storm in Guizhou on April 5, 2017 for example, the diagnosis analysis used the water vapor cloud and the initial field of EC thin grid, including physical quantity, surface and upper air meteorological observation, as well as radar observation data. For the environment parameter analysis, small CAPE value tended to underestimate storm intensity on potential forecast stage, strong vertical wind shear revealed the strong dry cold air was the important intensity factors of the storm. The water vapor cloud map can be used to monitor the most important features, the dry zone, the wet zone and the boundary between them. When dry intrusion is found, it can be used as one of the bases for the development of heavy rain. Dry cold air intrusion on high-level was traced by water vapor images. And in this process, the analyses revealed the role of dry cold air’s influence on intensity of the storm.

Indoor Environmental Quality of Air Conditioned Residential Buildings in Extreme Dry Desert Climate

In this study, the indoor environmental quality (IEQ) in air conditioned residential buildings in a dry desert climate is examined from the perspective of occupants via two aspects: thermal comfort and indoor air quality. The study presents statistical data about the domestic-occupant thermal comfort sensations together with data describing the indoor air quality in Kuwaiti residential buildings. With respect to the latter, the overall IEQ acceptance using two measurements namely: physical measurements and subjective information collected via questionnaires, was used to evaluate 111 occupants living in twenty five air-conditioned residential buildings in the state of Kuwait. The operative temperature based on Actual Mean Vote (AMV) and Predicted Mean Vote (PMV) was identified using linear regression analysis of responses on the ASHRAE seven-point thermal sensation scale and was found to be 25.2°C and 23.3°C, respectively, in the summer season. Indoor air quality (IAQ) with respect to carbon dioxide concentration level was compared with the acceptable limits of international standards, i.e. ASHRAE Standard 62.1 [1]. The proposed overall IEQ acceptance findings in residential buildings show CO2 concentration level between 909 and 1250 ppm. However, this may be considered a higher level of CO2 concentration, which may require increasing ventilation rate through window operation or mechanical ventilation.

Surface Roughness Evaluation in Dry-Cutting of Magnesium Alloy by Air Pressure Coolant

In this paper, a studying of surface roughness in dry milling with air pressure coolant of wrought magnesium alloy AZ31B will be carried out. The effects of air flow, feed-rate per tooth, cutting velocity and number of inserts in a cutting tool on surface roughness have been examined. Surface roughness increases with increasing feed-rate per tooth and increasing number of inserts in the cutting tool. However, it is nearly unchanged under a specific range of cutting velocity in the experiment and improved by the flow of air cooling.

Dry Intrusion Analysis of A Heavy Rainstorm in Southern Shaanxi

[Objective] One regional rainstorm weather in the south area of Shaanxi was expounded.[Method] By employing the NCEP/NCAR 1°×1°reanalysis data,routine observation and automatic precipitation station data,the large scale circulation background field of regional precipitation in the south area of Shaanxi province from July 16-18 in 2010 was expounded.By dint of physical quantity such as the meridional wind,relative humidity and false relative temperature,the characteristics of dry intrusion and its role in rainstorm were expounded.[Result] The mild and high latitude at 500 hPa was stable.The continental high pressure and subtropical high pressure were stable.The 700 and 850 hPa shear lines or low vortexes were the main influence system that resulted into large scale of rainstorm in south Shaanxi.The landing typhoon had distinct influences on the importance of storm.The influence of typhoon and subtropical high was mutual.It not only formed and strengthened the torrent in the low air,also transmitted water vapor and energy incessantly to the south area of Shaanxi,playing an important role in augment of rainstorm.There were two distinct dry intrusions in the rainstorm process,showing a dense dry layer in the high layer of convective layer.The existence of dry layer was conductive to the accumulation of convective unstable energy in the low layer.The release of convective unstable energy could transmit warm and wet airstream in the low level to the higher level,being conductive to the occurrence of precipitation.The analysis of θse in the warp direction vertical profile suggested that there was frontal zone in this rainstorm process and the dry air activity in this rainstorm process was very strong.[Conclusion] The study provided theoretical reference to the forecast in future.

一步式QuEChERS-气相色谱-三重四极杆质谱法快速测定风干牦牛肉中15种N-亚硝胺

建立了一步式QuEChERS自动提取和净化技术结合气相色谱-串联质谱同时测定风干牦牛肉中15种N-亚硝胺的分析方法。样品水化后,经乙腈提取,加入4.0 g MgSO_(4)和1.0 g NaCl除水,经十八烷基硅烷(C_(18))和N-丙基乙二胺(PSA)填料净化,采用DB-HeavyWAX色谱柱(30 m×0.25 mm×0.25μm)分离15种N-亚硝胺,在多重反应监测(MRM)模式下进行测定,外标法定量。结果表明,15种N-亚硝胺分离性能良好,在0.1~200μg/L范围内线性关系良好,相关系数(r^(2))≥0.999 0;检出限(LOD)为0.05~0.20μg/kg,定量限(LOQ)为0.10~0.50μg/kg;在1倍、2倍和10倍LOQ 3个添加水平下的平均回收率分别为79.4%~102.1%、80.6%~109.5%、83.0%~110.6%,相对标准偏差(RSD)为0.8%~16.0%。应用建立的方法检测2种不同加工工艺的市售样品,其中7种N-亚硝胺类化合物(N-亚硝基二甲胺、N-亚硝基二异丁胺、N-亚硝基二正丁胺、N-亚硝基甲基苯胺、N-亚硝基乙基苯胺、N-亚硝基吡咯烷、N-亚硝基二苯胺)均有不同程度检出,平均含量为0.08~20.18μg/kg,且熟制风干牦牛肉中N-亚硝胺的检出率和平均含量均高于传统生制风干牦牛肉。该方法实现了前处理的自动化,相较于其他传统方法,操作简单,实验效率高,人为影响因素小,检测灵敏度高,适用于风干牦牛肉中15种N-亚硝胺的快速测定,为研究肉制品中N-亚硝胺的测定提供了方法支持。

切片厚度和护色处理对热风干燥雪花梨干品质的影响

采用热风干燥法制备雪花梨干。以色泽、硬度、弹性、咀嚼性、总酚、总黄酮、可溶性糖和感官评分为评价指标,考察切片厚度(3、4、5、6、7、8 mm)和护色处理(CaCl_(2)、NaCl、D-异抗坏血酸钠、柠檬酸溶液浸泡、热烫)对梨干品质的影响,并以Z-score(Z值)综合模型进行评价,优选出适宜的切片厚度和护色处理。结果表明:随着切片厚度的增加,梨干的颜色变深,硬度、弹性和咀嚼性增大,总酚和总黄酮含量降低,可溶性糖含量增加;Z-score综合模型评价结果显示,切片厚度为4 mm时,Z值总和最高。护色处理均能改善梨干色泽,提高总酚和总黄酮含量,但可溶性糖含量降低。D-异抗坏血酸钠处理组梨干的亮度值(L^(*))最高,红绿值(a^(*))和蓝黄值(b^(*))最低,色差值(ΔE)最小;CaCl_(2)处理提高了梨干的硬度;热烫处理降低了梨干的弹性和咀嚼性。Z-score综合模型评价结果显示,以0.8 g/100 mL D-异抗坏血酸钠溶液浸泡护色的Z值总和最高。综上,热风干燥制备雪花梨干的厚度和护色条件为:切片厚度4 mm、0.8 g/100 mL D-异抗坏血酸钠溶液浸泡10 min。

风干肉不同条件贮藏品质研究

目的:探究风干肉的加工优化方案及不同条件贮藏对风干肉品质的影响。方法:以风干肉猪肉为研究对象,探究不同包装方式、不同贮藏温度对风干肉贮藏特性的影响。结果:随着贮藏时间的延长,不同包装方式下的风干肉的过氧化值(Peroxidation Value,POV)和菌落总数呈现上升趋势,pH值先降低后升高。与普通包装相比,气调包装和真空包装可以较好地保持风干肉的质量,其中真空包装的风干肉贮藏时间更长。4℃贮藏的风干肉品质变化较为缓慢,25℃和40℃贮藏的风干肉品质变化加快,其中40℃贮藏的风干肉保质期最短。结论:风干肉采用真空包装在4℃下贮藏有利于保障风干肉的品质。

Effects of Different Drying Processes on the Effective Components of Stichopus japonicus Viscera

Drying is a basic link in seafood processing, and the effects of forced air drying and vacuum drying on the effective components of Stichopus japonicus viscera were compared with the moisture, total saponin and polysaccharide contents as the detection indexes. The contents of effective components obtained using forced air drying were slightly lower than those obtained using vacuum drying, but the forced air drying method used short drying time and low economic energy consumption. Excellent drying effects and low cost of forced air drying made it can be adapted to the requirements of large-scale production applications.