Застосування сучасних прикладних комп'ютерних програм розширює можливість проведення многокомпонетного статистичного аналізу в матеріалознавстві. В роботі розглянуто процедуру застосування методу множинного кореляційно-регресійного аналізу для дослідження і моделювання багатофакторних зв'язків фізичних характеристик у кристалічних структурах. Розгляд здійснено на прикладі монокристалів нелегованого арсеніду галію. У виконаному статистичному аналізі був задіяний комплекс із семи фізичних характеристик, отриманих неруйнівними методами для кожної з 32 точок вздовж діаметра кристалічної пластини. Масив даних досліджувався методами множинного кореляційного аналізу. Була побудована розрахункова модель регресійного аналізу. На її основі з використанням програм Excel, STADIA і SPSS Statistics 17.0 проведено статистичну обробку даних і аналітичне вивчення взаємозв'язків всіх характеристик. Отримано і проаналізовано регресійні співвідношення при визначенні концентрації фонової домішки вуглецю, залишкових механічних напружень і концентрації фонової домішки кремнію. Була встановлена можливість коректного проведення множинного статистичного аналізу для моделювання властивостей кристала GaAs. Виявлено нові взаємозв'язки між параметрами кристала GaAs. Встановлено, що концентрація фонової домішки кремнію пов'язана з вакансійним складом кристала і значенням концентрації центів EL2. Також встановлено відсутність зв'язку концентрації кремнію з величиною залишкових механічних напружень. Ці факти і термічні умови формування точкових дефектів при вирощуванні монокристалів свідчать про відсутність перерозподілу фонових домішок в процесі охолодження кристала нелегованого GaAs. Використання методу множинного регресійного аналізу в матеріалознавстві дозволяє не тільки моделювати багатофакторні зв'язки в бінарних кристалах, а й здійснювати стохастичне моделювання факторних систем змінного складу Ключові слова: кореляційно-регресійний аналіз, множинна регресія, арсенід галію, кристалічна структура
When measuring the thermal conductivity of thermal insulation materials made by powder metallurgy and building porous materials, complications arise due to the fact that heat flows through the samples are commensurate with heat losses. The steady-state heat flow (SSHF) method is simple, does not require sophisticated equipment, and allows determining the thermal conductivity not in the near-surface layer but in the entire sample volume. Its disadvantage is low accuracy and the need to use reference samples. This work aims to develop an installation for measuring the thermal conductivity of largesized samples of low-conductivity material using the steady-state heat flow method with significantly higher accuracy than existing installations using this method. This is achieved by sandwiching the sample, which is a thin square plate of large dimensions, between the heater chamber and the refrigerator. The heating chamber is made of insulating material and its front wall, which is in contact with the sample, is made of the copper plate (which has good thermal conductivity). In the operating mode, the temperature in the heater chamber is maintained equal to the ambient temperature, which allows us to neglect heat losses and assume that in the steady-state mode, the heater power is equal to the heat flux through the sample. The thickness of the sample is much smaller than the size of its side (the sample should be square). This assumption is necessary to use the condition of isotropic temperature distribution in the cross-section of the sample. The refrigerator is filled with water and ice. The isotropic temperature distribution in the sample is ensured by its contact with the copper walls of the heater and refrigerator chamber. The temperature of the heated surface of the sample is measured using a thermocouple inserted through a hole in the front wall of the heater chamber. The proposed design of the installation and its operating conditions make it possible to significantly improve the accuracy of determining the thermal conductivity coefficient and make the error less than 2%.
To calculate the share of thermal energy consumed by this apartment in an apartment building, it is necessary to determine the heat transfer of all heating radiators in the house. But the heat transfer given in the passport of the heating device corresponds to the temperature pressure equal to 70K. Often the owners install non-standard devices, so the problem of determining the heat transfer of heating radiators in real conditions is relevant. Thermometric method, which is called electric, is widely used for laboratory determination of heat transfer of heating devices. Water by means of the pump circulates through an electric copper and the investigated radiator. The heat output of the latter is defined as the difference between the supplied electrical power (boiler power plus pump) and heat loss. The purpose of the work is to develop and study the operation of the installation for determining the heat transfer of heating radiators, which had a simpler design and could ensure proper measurement accuracy. We have proposed a scheme and design of the installation for determining the heat transfer of electric heating radiators, which differs in that it does not include a circulating pump. Water in the system circulates under the action of gravity due to changes in the density of the coolant during heating and cooling. This greatly simplifies the circuit by eliminating not only the pump but also the valve and the air outlet valve. The heater chamber is made of a steel pipe with a diameter of 88 mm. A steel cover is attached to the lower flange, through which a 1-1.5 kW heater is introduced into the chamber. Two 1/2 ″ sections of pipe are welded to the body of the heater chamber, through which the radiator is connected by means of rubber couplings. The cylindrical surface of the chamber on top of the layer of internal insulation is covered with a shielding heater, the temperature of which is maintained equal to the surface temperature of the heater chamber in the middle part. A layer of external thermal insulation is installed on top of the shielding heater. To determine heat loss, the radiator is disconnected from the heater chamber, plugs are installed and insulated. In stationary mode, the dependence of the heater power on the temperature of the heater chamber is measured, which determines the power of heat losses. The simplification of the installation has led not only to its reduction in price, but also to an increase in accuracy due to the reduction of heat losses and the simplicity of their definition.
The object of research is the crystal structure of the Ba3TeO6 compound. It is known from the literature that this material has photoluminescent properties and crystallizes in the tetragonal system with the space symmetry group I41/a (88) and lattice periods a=19.3878 А; b=19.3878 Аº, c=34.909 Аº. At the same time, there are data on two other polymorphic modifications of this compound, which are in the PDF-2 database for 2009. Therefore, information about the crystal structure of this compound is incomplete. The existence of different spectra for a given compound mentioned in the literature may be due to different methods of synthesis of this compound. A study of the crystal structure of the compound Ba3TeO6 under the number 00-035-0995 in the PDF-2 database for 2009 is proposed. The study used the 2009 PDF-2 database. As well as the HighScorePlus 3.0 program (Netherlands), which makes it possible to refine the microstructural parameters of a structural model using the Rietveld method. The diffraction spectrum for the study was generated using the HighScorePlus 3.0 program and the 2009 pdf-2 database connected to it in UDF format. As a result, it was found that this diffraction spectrum of the studied compound can correspond to the following structural model: orthorhombic system with lattice periods a=4.2910 A; b=4.4062 A; c=4.3459 A. The space symmetry group Pnnn(48) is possible. Analyzing the results obtained, it should be recognized that the studied structure of the compound crystallizes in its own structural type. At the same time, the crystal structures of the polymorphic modifications of this compound are similar. The study of the crystal structure of the compound contributes to a better understanding of its physical properties, in particular, photoluminescence
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