利用热时模型研究贮存时间和环境温度对烟支白度的影响

分析了贮存温度对全国6个城市贮存的7种卷烟产品烟支外观质量的影响,发现卷烟烟支表面发生较明显的质量变化起始温度为15℃。建立了42个样品的烟支白度与热时的线性回归模型,模型显示白度与温度呈较好的线性关系,随着热时的增加,卷烟白度明显降低。样品S1在6个贮存城市的白度和热时的拟合结果表明,城市贮存温度不同烟支白度变化速度不一致。

陕西苹果花期机理性预报模型的适用性评价

以陕西苹果花期为研究对象,针对4个机理性物候模型--顺序模型(SM)、平行模型(PM)、深度休息模型(DRM)和热时模型(TTM),基于各果区代表站的花期数据及同期气象数据订正模型参数,利用内部检验和交叉验证(留一验证)方法,评价模型在模拟花期上的适用性。结果表明:内部检验时各站点的最适模型不同,总体上,SM和TTM均方根误差略低(3.30 d);交叉验证时模型表现相当,各模型平均的均方根误差为4.52 d,略优于内部检验。使用单站外推和求平均后外推将TTM参数应用至果区内其他站,这两种方法的均方根误差均优于国外同类研究(10.0 d),其中单站外推的均方根误差(5.90 d)又高于求平均后外推(7.21 d)。综合考虑模型的复杂性与模拟精度,推荐使用TTM并分果区模拟陕西苹果花期。

山西阳高杏花期前气温对花期的影响及花期冻害风险分析

利用1981—2021年山西省大同市杏主产区阳高县的气象观测站资料,分析了杏开花前气温对花期的影响;采用热时模型利用日平均气温重构阳高县杏花期,分析了模型的可行性;按照杏花冻害指标阈值提取重度、中度、轻度3个等级冻害终日,采用线性趋势法和风险等级划分法,分析阳高县杏花期冻害风险。结果表明:花期前不同时段气温与花期日序数呈负相关;应用热时模型重构的花期亦呈提前趋势;重度、总冻害风险在降低,而轻度、中度冻害风险呈弱的增加趋势。

陕西苹果主产县花期冻害风险评估

为评估陕西礼泉和旬邑两个苹果主产县富士苹果的花期冻害风险,通过热时模型利用日平均气温重构礼泉和旬邑两地1967-2018年苹果始花期,并利用日最低气温根据苹果花期冻害指标阈值提取两地同时期内重度、中度和轻度不同等级冻害终日,采用线性倾向法和风险指数法分析两地苹果花期冻害风险情况。结果表明:1967-2018年礼泉和旬邑的重构苹果始花期呈显著提前趋势,提前速率分别为2.8d·10a^−1(P<0.01)和0.8d·10a^−1(P<0.05);礼泉地区重度冻害终日呈显著提前趋势,提前速率为3.3d·10a^−1(P<0.01),中度、轻度冻害终日无显著变化,旬邑地区三个等级冻害终日均无显著变化;礼泉地区苹果平均始花期日序为DOY100,晚于平均轻度冻害终日日序DOY95,冻害风险较小,旬邑地区苹果平均始花期日序为DOY107,晚于平均重度冻害终日日序DOY93,但早于平均轻度冻害终日日序DOY118,冻害风险较高;礼泉和旬邑两地苹果花期冻害风险指数无显著变化,但是两地冻害风险指数≥0的频次增加,说明苹果花期冻害风险有上升趋势。

Numerical method and model for calculating thermal storage time for an annular tube with phase change material

For calculating the thermal storage time for an annular tube with phase change material （PCM）, a novel method is proposed. The method is suitable for either low-temperature PCM or high-temperature PCM whose initial temperature is near the melting point. The deviation fit is smaller than 8% when the time is below 2x104 s. Comparison between the predictions and the reported experimental data of thermal storage time at same conditions is investigated and good agreements have been got. Based on this method, the performance of the thermal storage unit and the role of natural convection are also investigated. Results show a linear relation between the maximum amount of stored heat and thermal storage time, and their ratio increases with the height of the thermal storage unit. As the thickness of the cavity increases, natural convection plays an increasingly important role in promoting the melting behavior of paraffin. When the thickness of the cavity is small, natural convection restrains the melting behavior of paraffin.

Equation oriented method for Rectisol wash modeling and analysis

Rectisol process is more efficient in comparison with other physical or chemical absorption methods for gas purification. To implement a real time simulation of Rectisol process, thermodynamic model and simulation strategy are needed. In this paper, a method of modified statistical associated fluid theory with perturbation theory is used to predict thermodynamic behavior of process. As Rectisol process is a highly heat-integrated process with many loops, a method of equation oriented strategy, sequential quadratic programming, is used as the solver and the process converges perfectly. Then analyses are conducted with this simulator.

Numerical and experimental evaluation on methods for parameter identification of thermal response tests

Several parameter identification methods of thermal response test were evaluated through numerical and experimental study.A three-dimensional finite-volume numerical model was established under the assumption that the soil thermal conductivity had been known in the simulation of thermal response test.The thermal response curve was firstly obtained through numerical calculation.Then,the accuracy of the numerical model was verified with measured data obtained through a thermal response test.Based on the numerical and experimental thermal response curves,the thermal conductivity of the soil was calculated by different parameter identification methods.The calculated results were compared with the assumed value and then the accuracy of these methods was evaluated.Furthermore,the effects of test time,variable data quality,borehole radius,initial ground temperature,and heat injection rate were analyzed.The results show that the method based on cylinder-source model has a low precision and the identified thermal conductivity decreases with an increase in borehole radius.For parameter estimation,the measuring accuracy of the initial temperature of the deep ground soil has greater effect on identified thermal conductivity.

Prediction Model for Cooling of an Electrical Unit with Time-Dependent Heat Generation

The satisfactory performance of electrical equipments depends on their operating temperature. In order to maintain these devices within the safe temperature limits, an effective cooling is needed. High heat transfer rate of compact in size and reliable operation are the challenges of a thermal design engineer of electronic equipment. Then, it has been simulated the transient a three-dimensional model to study the heating phenomenon with two assumption values of heat generation. To control for the working of this equipment, cooling process was modeled by choosing one from different cooling technique. Constant low speed fan at one direction of air flow was used for cooling to predict the reducing of heating temperature through working of this equipment. Numerical Solution of finite difference time domain method （FDTD） has been utilized to simulate the temporal and spatial temperature profiles through two processes, which would minimize the solution errors.

On Models of Nonlinear Evolution Paths in Adiabatic Quantum Algorithms

In this paper,we study two different nonlinear interpolating paths in adiabatic evolution algorithms for solving a particular class of quantum search problems where both the initial and final Hamiltonian are one-dimensional projector Hamiltonians on the corresponding ground state.If the overlap between the initial state and final state of the quantum system is not equal to zero,both of these models can provide a constant time speedup over the usual adiabatic algorithms by increasing some another corresponding "complexity".But when the initial state has a zero overlap with the solution state in the problem,the second model leads to an infinite time complexity of the algorithm for whatever interpolating functions being applied while the first one can still provide a constant running time.However,inspired by a related reference,a variant of the first model can be constructed which also fails for the problem when the overlap is exactly equal to zero if we want to make up the "intrinsic" fault of the second model - an increase in energy.Two concrete theorems are given to serve as explanations why neither of these two models can improve the usual adiabatic evolution algorithms for the phenomenon above.These just tell us what should be noted when using certain nonlinear evolution paths in adiabatic quantum algorithms for some special kind of problems.

The IOCAS intermediate coupled model(IOCAS ICM) and its real-time predictions of the 2015–2016 El Nio event

The tropical Pacific is currently experiencing an El Nifio event. Various coupled models with different degrees of complexity have been used to make real-time E1 Nifio predictions, but large uncertainties exist in the inten- sity forecast and are strongly model dependent. An intermediate coupled model （ICM） is used at the Institute of Oceanology, Chinese Academy of Sciences （IOCAS）, named the IOCAS ICM, to predict the sea surface temper- ature （SST） evolution in the tropical Pacific during the 2015-2016 E! Nifio event. One unique feature of the IOCAS ICM is the way in which the temperature of subsurface water entrained in the mixed layer （Te） is parameterized. Observed SST anomalies are only field that is utilized to initialize the coupled prediction using the IOCAS ICM. Examples are given of the model＇s ability to predict the SST conditions in a real-time manner. As is commonly evident in E1 Nifio- Southern Oscillation predictions using coupled models, large discrepancies occur between the observed and pre- dicted SST anomalies in spring 2015. Starting from early summer 2015, the model can realistically predict warming conditions. Thereafter, good predictions can be made through the summer and fall seasons of 2015. A transition to normal and cold conditions is predictecl to occur in rote spring 2016. Comparisons with other model predictions are made and factors influencing the prediction performance of the IOCAS ICM are also discussed.

On a Nonlinear Model in Adiabatic Evolutions

In this paper, we study a kind of nonlinear model of adiabatic evolution in quantum search problem. As will be seen here, for this problem, there always exists a possibility that this nonlinear model can successfully solve the problem, while the linear model can not. Also in the same setting, when the overlap between the initial state and the final stare is sufficiently large, a simple linear adiabatic evolution can achieve O(1) time efficiency, but infinite time complexity for the nonlinear model of adiabatic evolution is needed. This tells us, it is not always a wise choice to use nonlinear interpolations in adiabatic algorithms. Sometimes, simple linear adiabatic evolutions may be sufficient for using.

Efficiency at Maximum Power Output of a Quantum-Mechanical Brayton Cycle

The performance in finite time of a quantum-mechanical Brayton engine cycle is discussed, without intro- duction of temperature. The engine model consists of two quantum isoenergetic and two quantum isobaric processes, and works with a single particle in a harmonic trap. Directly employing the finite-time thermodynamics, the efficiency at maximum power output is determined. Extending the harmonic trap to a power-law trap, we find that the efficiency at max/mum power is independent of any parameter involved in the model, but depends on the confinement of the trapping potential.