Analysis of piezoelectric semiconductor fibers under gradient temperature changes

Piezoelectric semiconductors(PSs)possess both semiconducting properties and piezoelectric coupling effects,making them optimal building blocks for semiconductor devices.PS fiber-like structures have wide applications in multi-functional semiconductor devices.In this paper,a one-dimensional(1D)theoretical model is established to describe the piezotronic responses of a PS fiber under gradient temperature changes.The theoretical model aims to explain the mechanism behind the resistance change caused by such gradient temperature changes.Numerical results demonstrate that a gradient temperature change significantly affects the physical fields within the PS fiber,and can induce changes in its surface resistance.It provides important theoretical guidance on the development of piezotronic devices that are sensitive to temperature effects.

DAMAGE DETECTION FOR COMPOSITE STRUCTURE UNDER TEMPERATURE CHANGES USING LAMB WAVES

A two-step method is proposed for detection and identification of invisible impact damage in composite structure under temperature changes using Lamb waves.First,a statistical outlier analysis is employed to distinguish whether the changes of Lamb wave signals are induced by damage within a monitoring area or are only affected by temperature changes.Damage indices are defined after the Lamb wave signals are processed by Fourier transform,and a Monte Carlo procedure is used to obtain the damage threshold value for the damage indices at the undamaged state.If the damage indices in the operation state exceed the threshold value,the presence of damage is determined.Then,a probabilistic damage imaging algorithm displaying probabilities of the presence of damage within the monitoring area is adopted to fuse information collected from multiple actuator-sensor paths to identify the location of damage.Damage indices under damaged state are used to generate the diagnostic image.Experimental study on a stiffened composite panel with random temperature changes is performed to demonstrate the effectiveness of the proposed method.

An Updated Estimation of Radiative Forcing due to CO_2 and Its Effect on Global Surface Temperature Change

New estimations of radiative forcing due to CO2 were calculated using updated concentration data of CO2 and a high-resolution radiative transfer model. The stratospheric adjusted radiative forcing （ARF） due to CO2 from the year 1750 to the updated year of 2010 was found to have increased to 1.95 W m-2, which was 17% larger than that of the IPCC＇s 4th Assessment Report because of the rapid increase in CO2 concentrations since 2005. A new formula is proposed to accurately describe the relationship between the ARF of CO2 and its concentration. Furthermore, according to the relationship between the ARF and surface temperature change, possible changes in equilibrium surface temperature were estimated under the scenarios that the concentration of CO2 increases to 1.5, 2, 2.5, 3, 3.5 and 4 times that of the concentration in the year 2008. The result was values of ＋2.2℃, ＋3.8℃, ＋5.1℃, ＋6.2℃, ＋7.1℃ and ＋8.0℃ respectively, based on a middle-level climate sensitivity parameter of 0.8 K （W m 3）-1. Non-equilibrium surface temperature changes over the next 500 years were also calculated under two kinds of emission scenarios （pulsed and sustained emissions） as a comparison, according to the Absolute Global Temperature change Potential （AGTP） of CO2. Results showed that CO2 will likely continue to contribute to global warming if no emission controls are imposed, and the effect on the Earth-atmosphere system will be difficult to restore to its original level.

Impact of Increasing Stratospheric Water Vapor on Ozone Depletion and Temperature Change

Using a detailed, fully coupled chemistry climate model （CCM）, the effect of increasing stratospheric H20 on ozone and temperature is investigated. Different CCM time-slice runs have been performed to investigate the chemical and radiative impacts of an assumed 2 ppmv increase in H20. The chemical effects of this H20 increase lead to an overall decrease of the total column ozone （TCO） by ～1% in the tropics and by a maximum of 12% at southern high latitudes. At northern high latitudes, the TCO is increased by only up to 5% due to stronger transport in the Arctic. A 2-ppmv H2O increase in the model＇s radiation scheme causes a cooling of the tropical stratosphere of no more than 2 K, but a cooling of more than 4 K at high latitudes. Consequently, the TCO is increased by about 2%-6%. Increasing stratospheric H2O, therefore, cools the stratosphere both directly and indirectly, except in the polar regions where the temperature responds differently due to feedbacks between ozone and H2O changes. The combined chemical and radiative effects of increasing H2O may give rise to more cooling in the tropics and middle latitudes but less cooling in the polar stratosphere. The combined effects of H2O increases on ozone tend to offset each other, except in the Arctic stratosphere where both the radiative and chemical impacts give rise to increased ozone. The chemical and radiative effects of increasing H2O cause dynamical responses in the stratosphere with an evident hemispheric asymmetry. In terms of ozone recovery, increasing the stratospheric H2O is likely to accelerate the recovery in the northern high latitudes and delay it in the southern high latitudes. The modeled ozone recovery is more significant between 2000 ～2050 than between 2050～2100, driven mainly by the larger relative change in chlorine in the earlier period.

The Effects of Rapid Temperature Changes on HK,PK and HSP70 of Litopenaeus vannamei in Different Seasons

Activities of hexokinase(HK),pyruvate kinase(PK) and levels of HSP70 were measured to evaluate the response of Litopenaeus vannamei to rapid temperature changes under controlled laboratory conditions.Shrimps were subjected to a quick temperature change from 27℃ to 17℃ for the summer case(Cold temperature treatment),or from 17℃ to 27℃ for the winter case(Warm temperature treatment).After 0.5,1,3,6,12,24,48,and 72 h of exposure time,shrimps were sampled and prepared for further analysis.The results showed that the effect of acute temperature changes on activities of HK was significant.Patterns of variations of the two glycolytic enzymes suggested that enzymes in the glycolysis cycle could adjust their activities to meet the acute temperature change.The HSP70 level increased in both cold and warm temperature treatments,suggesting that the rapid temperature changes activated the process of body's self-protection.But the difference in expression peak of HSP70 might be related to the different body size and the higher thermal sensitivity to temperature increase than to temperature decrease of L.vannamei.

Effects of Periodic Temperature Changes on Stress Relaxation of Chemically Treated Wood

In order to clarify the relationship between the microstructural changes and the rheological behaviors of four chemically treated woods (delignified wood, hemicellulose-removed wood, DMSO swollen and decrystallization treated wood), the stress relaxation of wood with three different moisture contents was determined during periodic temperature changes. The experi- mental results show that after wood relaxation for 4 h at 25 °C, the stress decays sharply when the temperature increases and 2 h later the stress recovers again when the temperature drops back to the original point. The additional stress relaxation, produced after tem- perature begins to increase, is mainly caused by the thermal swelling, molecular thermal movement and the break of a part of residual hydrogen bonds. The number of hydrogen bonds and the size and amount of cavities in various treated woods greatly affect the magnitude of the additional relaxed stress and the recovery stress.

Effects of temperature change on elastic behavior of steel beams with semi-rigid connections

Based on the nonlinear displacement-strain relationship,the virtual work principle method was used to establish the nonlinear equilibrium equations of steel beams with semi-rigid connections under vertical uniform loads and temperature change.Considering the non-uniform temperature distribution across the thickness of beams,the formulas for stresses and vertical displacements were presented.On the basis of a flowchart for analysis of the numerical example,the effect of temperature change on the elastic behavior of steel beams was investigated.It is found that the maximal stress is mainly influenced by axial temperature change,and the maximal vertical displacement is principally affected by temperature gradients.And the effect of temperature gradients on the maximal vertical displacement decreases with the increase of rotational stiffness of joints.Both the maximal stress and vertical displacement decrease with the increase of rotational stiffness of joints.It can be concluded that the effects of temperature changes and rotational stiffness of joints on the elastic behavior of steel beams are significant.However,the influence of rotational stiffness becomes smaller when the rotational stiffness is larger.

Analysis of Surface Air Temperature Change in Macao During the Period 1901-2007

Change related to climate in Macao was studied on the basis of daily temperature observations over the period 1901-2007. The result shows that annual mean surface air temperature in Macao as a whole rose with a warming rate of about 0.066℃ per 10 years in the recent 107 years. The most evident warming occurred in spring and winter. The interdecadal variations of the seasonal mean temperature in summer and winter appeared as a series of waves with a time scale of about 30 years and 60 years, respectively. The annual mean minimum temperature increased about twice as fast as the annual mean maximum temperature, resulting in a broad decline in the annual mean diurnal range. The interdecadal variations of annual mean maximum temperature are obviously different from those of annual mean minimum temperature. It appears that the increase in the annual mean maximum temperature in the recent 20 years may be part of slow climate fluctuations with a periodicity of about 60 years, whereas that in the annual mean minimum temperature appears to be the continuation of a long-term warming trend.

Primary Analysis of the Causes of Temperature Changes after Songjiang Observation Station Transferring

Temperatures of the old station and the new one in Songjiang were compared with each other,and data via automatic weather station instead of manual observation after transferring were also analyzed.The results showed that the average temperature,the minimum temperature,the maximum temperature and the extreme temperature in the new observation station were all higher than those in the old one.The average temperature difference of the new observation and the old one from 20:00 to 08:00 of the next day was bigger than that from 08:00 to 20:00.There were two causes of temperature changes after Songjiang station transferring:one was that two stations were affected by the surrounding environment and the nature of underlying surface,and the other was that theory of sensing part,observation time and process were different between the automatic weather station and the manual observation.

Characteristics of Temperature Change in China over the Last 2000 years and Spatial Patterns of Dryness/Wetness during Cold and Warm Periods

This paper presents new high-resolution proxies and paleoclimatic reconstructions for studying climate changes in China for the past 2000 years. Multi-proxy synthesized reconstructions show that temperature variation in China has exhibited significant 50–70-yr, 100–120-yr, and 200–250-yr cycles. Results also show that the amplitudes of decadal and centennial temperature variation were 1.3℃ and 0.7℃, respectively, with the latter significantly correlated with long-term changes in solar radiation, especially cold periods, which correspond approximately to sunspot minima. The most rapid warming in China occurred over AD 1870–2000, at a rate of 0.56°± 0.42℃（100 yr）^（-1）; however, temperatures recorded in the 20 th century may not be unprecedented for the last 2000 years, as data show records for the periods AD 981–1100 and AD1201–70 are comparable to the present. The ensemble means of dryness/wetness spatial patterns in eastern China across all centennial warm periods illustrate a tripole pattern： dry south of 25°N, wet from 25°–30°N, and dry to the north of 30°N. However, for all centennial cold periods, this spatial pattern also exhibits a meridional distribution. The increase in precipitation over the monsoonal regions of China associated with the 20 th century warming can primarily be attributed to a mega El Nino–Southern Oscillation and the Atlantic Multidecadal Oscillation. In addition, a significant association between increasing numbers of locusts and dry/cold conditions is found in eastern China. Plague intensity also generally increases in concert with wetness in northern China, while more precipitation is likely to have a negative effect in southern China.

Adiabatic Temperature Changes in (Gd_(1-x)Ho_x)_5Si_4 Magnetic Refrigeration Materials

A series of alloys (Gd1-xHox)5Si4(x=0, 0.05, 0.15, 0.25) have been prepared. Adiabatic temperature changes of(Gd1-xHox)5Si4 alloys is exactly investigated by a control and analysis system for ΔH=1.4 T, and the measurement results are trustworthy. Curie temperatures of these alloys are tunable in a wide temperature region, and decrease almost linearly with the increasing of Ho content. Magnetic entropy changes in the (Gd1-xHox)Si4 compounds are about 2.35 J/(kg·K) when magnetic field change are 0～1.4 T. The adiabatic temperatures of these alloys at Curie Points are larger than 1 K about 40% of that of Gd in a field change 0～1.4 T, and the curves of ΔTad are as wide as that of Gd. The relative cooling power RCP(S) or RCP(T) of these alloys are about 0.5～0.7 J·cm-3 and 42～50 K2 on the field 0～1.4 T, about 58% and 55% of that of Gd respectively. These alloys are potential magnetic refrigerants working in a refrigerator at room temperatures.

Effects of temperature change on the rheological property of modified multiwall carbon nanotubes

Solvent-free nanofluids hold promise for many technologically significant applications.The liquid-like behavior,a typical rheological property of solvent-free nanofluids,has aroused considerable interests.However,there has been still lack of efficient methods to predict and control the liquid-like behavior of solvent-free nanofluids.In this paper,we propose a semi-discrete dynamic system with stochastic excitation describing the temperature change effects on the rheological property of multiwall carbon nanotubes(MWCNTs)modified by grafting sulfonic acid terminated organosilanes as corona and tertiary amine as canopy,which is a typical covalent-type solvent-free nanofluid system.The vibration of the grafting branches is simulated by employing a structure-preserving approach,and the shear force of grafting branches at the fixed end is computed subsequently.By taking the shear forces as an excitation acting on the MWCNTs,the axial motion of the MWCNTs is solved with the 7-point Gauss-Kronrod quadrature rule.The critical temperature associated with the appearance of the liquid-like behavior as well as the upper bound of the moving speed of the modified MWCNTs is determined,which can be used to predict and control the liquid-like behavior of the modified MWCNTs in engineering applications.

Average Annual Temperature Changes in the Holocene in China

Abstract: In 1876 Blytt proposed a post-glacial climatic classification, maintaining that the then temperature fluctuated 1–2°C higher or lower than that today. Lamb (1969) held that in Europe “the axis of the subtropical high pressure belt was generally displaced north by about 10° latitudes” during the Hypsithermal and that the temperature was three to six times higher than that in the postglacial period.

Effects of Coal Mining Subsided Water Area on Temperature Change in Huaibei Coal Mine

[Objective] The study aimed to discuss the effects of coal mining subsided water area on temperature change in Huaibei coal mine. [Method] Based on the data of monthly temperature from 1957 to 2007 recorded by Suixi （coal mining subsided water area） and Fuyang stations （control）, the effects of coal mining subsided water area on temperature change in Huaibei coal mine were discussed using linear trend estimation and comparative analysis methods. [Result] Spring, autumn, winter and annual average temperatures of coal mining subsided water area （Suixi） were increased in the last 51 years, and the increase of winter temperature was mostly significant with a tendency rate of 0.49 ℃/10 a. Meanwhile, annual temperature range of coal mining subsided water area was decreased from 1957 to 2007. Temperatures of Suixi in four seasons were lower than those of Fuyang from the 1960s to 1990s, and temperatures of coal mining subsided water area （Suixi） were higher than those of Fuyang in spring, autumn and winter but lower than those of Fuyang in summer from 2000 to 2007. [ Result] Coal mining subsided water area had certain effects on temperature change of Huaibei coal mine.

Temperature Changes in Typical Karst Area of Guangxi to Global Warming during 1971- 2013

The spatial and temporal variation characteristics of temperature were analyzed by using climate tendency coefficient, climatic inclination rate and Mann-Kendall catastrophe test,based on the annual and seasonal average temperatures of 28 meteorological stations in Guangxi from 1971 to 2013. Under the global warming,the annual and seasonal average temperatures in typical karst area of Guangxi had an increasing trend. The cli- mate inclination rate of annual average temperature reached a significant level, which was about 0.17 ℃/10 a, and the year of abrupt changes ap- peared in 1996. About seasonal temperature＇s trend, average temperatures of all the four seasons had an increase trend in the past 43 years, and the significant increase was happened in autumn with the temperature increase rate of 0.28 ℃/10 a, followed by increase rate of average tempera- ture in winter with 0.25 ℃/10 a. A long-term warming tendency was observed by seasonal average temperature from 1971 to 2013, especially dur- ing 2002 - 2013.

The Relationships between Respiratory Disease, Cardio-cerebral Vascular Disease and Temperature Change

Respiratory disease and cardio-cerebral vascular disease frequently occur in Anyang City. In this paper, by comparing incidence num- bers of respiratory disease and cardio-cerebral vascular disease in Anyang People＇s Hospital during 2010 -2012 with seasonal change of local tem- perature,it is found that they have obvious relationship, which has very important significance for preventing respiratory disease and cardio-cerebral vascular disease in the future.

Air Temperature Changes and Urbanization Contribution Ratio in Kunming City in Recent 50 Years

[Objective] The aim was to study air temperature changes and urbanization contribution ration in Kunming City in recent 50 years. [ Method] The observation data of air temperature series from Kunming station and other four surrounding meteorological stations were used to in- vestigate air temperature variation in Kunming station affected by urbanization during 1960 -2009. [ Result] The trend slope of mean annual temper- ature was 0.402 ~（3/10 a in Kunming station and 0. 103 ~C/10 a in other four surrounding meteorological stations, and the increasing magnitude of air temperature in Kunming station was more than 3 times that of average global warming in the past 50 year. The effect of urbanization on mean an- nual temperature in Kunming station started from 1990. During 1990 -1994, the increasing contribution rate of urbanization to air temperature in Kunming station was less than 40%. From 1995 to 2009, the contribution ratio was more than 50%, up to about 60% in all seasons. Urban heat is- land effect in Kunming station was intensified with the development of urbanization. In addition, the warming rate caused by urban heat island effect in Kunming station was the greatest in dry season, followed by mean annual temperature, and it was the weakest in rainy season. [ Conclusion] The study provided theoretical foundation for future research.

Free Vibration of Geometrically Nonlinear Functionally Graded Micro-switches under Electrostatic Force and Temperature Change

The free vibration characteristics of functionally graded micro-switches under combined electrostatic, axial residual stress and temperature change is investigated, with an emphasis on the effect of geometric nonlinear deformation due to mid-plane stretching, the influence of volume fraction profile parameter and temperature change. The micro-switch considered in this study is made of either homogeneous material or non-homogeneous functionally graded material with two material phases. Taking the temperature-dependency of the effective material properties into consideration, the Voigt model is used to simulate the material properties of the FGMs （functionally graded materials）. The principle of virtual work is used to derive the nonlinear governing differential equation. The eigenvalue problem which describes free vibration of the micro-beam at its statically deflected state is then solved using DQM （differential quadrature method）. The natural frequencies of clamped-clamped micro-switches are obtained. The solutions are validated through direct comparisons with experimental results reported in previous studies. A parametric study is conducted to show the effects of geometric nonlinearity, material composition, temperature change and geometrical parameters for the natural frequencies.

ON TEMPERATURE CHANGES OF SHANGHAI AND URBANIZATION IMPACTS

To understand how temperature varies in urban Shanghai under the background of global climate change and how it is affected by urbanization, the Shanghai temperature responses to global warming were analyzed, and then the temperature trends of urban and suburb stations under different climatic backgrounds were obtained. The urbanization effects on temperature were studied by comparing urban stations to suburb stations, the relationship between urbanization variables and temperature components were obtained, and observation data of surface and high level were combined to assess the contribution of urbanization effect. In the last part of the paper, the cause of urbanization effects on temperature was discussed. The results indicated: The long term change trend of Shanghai annual mean temperature is 1.31/100a from 1873 to 2004, the periods of 1921 – 1948 and 1979 – 2004 are warmer, and the 1979 – 2004 period is the warmest; compared to suburb stations, the representative urban station has slower decreases in the cool period and faster increases in the warm one; the urban and suburb temperatures have distinct differences resulting from urbanization and the differences are increasing by the year, with the difference of mean temperature and minimum temperature being the greatest in fall and that of maximum temperature being the largest in summer between the urban and suburban areas. The urbanization process accelerates the warming speed, with the minimum temperature being the most obvious; the urbanization effect contributes a 0.4°C increase in 1980s and 1.1°C in 1990s to the annual mean temperature.

Temperature change between neighboring days and hospital admissions in China

The short-term temperature fluctuation caused by global climate change is one of the risk factors affecting public health.Exploring the association between temperature fluctuation and diseases,which has received relatively limited research attention,can contribute to enhancing awareness of health risks and taking timely measures for health risk alert and management.Therefore,this study aims to investigate the relationship between temperature change between neighboring days(TCN)and hospitalizations,identify diseases sensitive to extreme TCN,and evaluate the related disease burden.We collected meteorological and hospitalization data from 2014 to 2019 in 23 sites of China to explore the impact of TCN on hospitalizations.We first quantified site-specific associations between TCN and hospitalizations and then conducted meta-analysis to pool the results,to assess the relative risk of extreme TCN for susceptible diseases,and to estimate the related disease burden attributed to TCN.Stratified analyses were undertaken by age,sex,and disease type.Results showed that all-cause hospital admission was significantly linked to TCN.A negative TCN(below-1.9℃)in the cool season and a positive TCN(above 1.0℃)in the warm season increased the risk of hospitalization.People aged 15-64 years,men,and patients with musculoskeletal system or connective tissue diseases were more sensitive to extremely negative TCN during the cool season.People aged over 65 years,men,and patients with respiratory diseases were more sensitive to extremely positive TCN during the warm season.The attributable fraction to all-cause hospitalization from negative TCN in the cool season was 2.05%(95%CI:-0.90%,4.53%)and from positive TCN in the warm season was 5.79%(95%CI:2.98%,8.31%).Circulatory diseases in the cool season and respiratory diseases in the warm season had the highest disease burden.Our findings indicate that awareness of TCN and its health risks should be promoted and evidence-informed policies are needed to reduce the risk of TCN.