The Effect Of Heating Acrylic Resin Of Various Types With Different Temperatures On Impact Strength

Resin polymerization which is affected by unstable temperature causes the resin to break easily. The strength of the base material is affected by the forces acting in the mouth, such as transverse forces, other resistance or fatigue, and flexibility. Fracture of denture caused by masticatory loads and is affected by forces acting in the mouth, including transverse, resistance or fatigue, and flexural forces. Experimental Laboratory total of 72 samples consisting of 18 samples of type A, B and C cured at normal temperature, 100oC, 200oC, and 300oC. Types A, B and C have the effect of heating with the addition of temperature on the impact strength of acrylic resin, because the value of sig = 0.001 < 0.05, so H0 is rejected. An effect with the addition of temperature on the impact strength of the resin types A, B and C, because sig = 0.001 < 0.05, so H0 is rejected, which means that the average results are significantly different due to differences in temperature.

Convective and Absolute Instabilities Induced by Viscous Dissipation in the Thermocapillary Convection with Through-Flow

The mixed convection in a thin liquid film flow over a horizontal plate is investigated under finite Prandtl numbers. The gas-liquid interface is considered free, non-deformable and subject to surface tension gradients and convection, while gravity is assumed negligible. Therefore, Marangoni instead of buoyancy effects appear due to the unstable temperature stratification induced by the internal heating generated by viscous dissipation. A linear and modal stability analysis of this model is then performed to identify its convective/absolute nature. This is achieved by solving the resulting differential eigenvalue problem with a shooting method. Longitudinal rolls are the most unstable at the onset of instability for most parametric conditions. Otherwise, transverse rolls are the first to become convectively unstable. Finally, longitudinal rolls are absolutely stable. A transition to absolute instability occurs through transverse rolls, but only within a limited region in parametric space.

Phase change materials and their use for energy accumulation

Problems with overheating and unstable temperature of industrial equipment are the reasons for generating significant costs that for companies. Solving the problems related to heat removal is a challenge in modern industry. Phase change materials are the solution to these challenges (PCM). These substances can accumulate and release large amounts of thermal energy during the phase change transition. The value of the phase transition enthalpy determines the energy storage capacity. The paper presents the results of phase transitions of selected materials. The measurements were carried out on a stand for testing phase change materials. The laboratory stand made it possible to determine the thermodynamic parameters of the phase transition. The substances analysed are kinds of paraffin of different chemical composition. Due to the diversity of substances, it is possible to analyse the influence of the chemical composition on possible uses in industrial applications for energy storage.

Marangoni convection of a viscous fluid over a vibrating plate

This research presents a new insight into Marangoni convection through investigating, both numerically and analytically, the surface tension driven instability activated by a coupled effect of a vibrating plate and viscous dissipation. A horizontal, thin fluid layer is bounded from below by an impermeable, adiabatic plate that vibrates in the horizontal direction. The upper boundary is modelled by a free surface subject to a thermal boundary condition of the third kind (Robin). The internal heat generation due to viscous dissipation yields a vertical, potentially unstable temperature gradient. The linear stability analysis of the stationary terms of the basic state is performed. The perturbed flow, in the form of plane waves, is superimposed onto the basic state. The obtained system of ordinary differential equations is solved numerically by means of the Runge–Kutta method coupled with the shooting method. For the two limiting cases, the isothermal upper boundary and adiabatic upper boundary, the analytical solutions of the eigenvalue problem are obtained. The values of the critical parameter, which identifies the threshold for the onset of Marangoni convection, are presented.

Monitoring System for Broiler Chicken Farms Based on Internet of Things (IoT)

In this study, the author made a monitoring system for dangerous gas levels, temperature and humidity in the chicken coop. This system can inform air quality in the form of ammonia gas, methane gas, temperature and humidity contained in the chicken coop and provide readings of gas data that are considered dangerous, unstable temperature and humidity to workers in the chicken coop and can be viewed on a platform basis. The system generally consists of two sensors, namely the DHT11 sensor to detect temperature and humidity in the chicken coop, and the MQ135 sensor to detect ammonia gas levels in the chicken coop, and connect to the internet network through the ESP8266 module with the Arduino Mega 2560 microcontroller which aims to upload data sensors to the Firebase web and displayed in graphical form as a means of information on the chicken coop. The test is carried out in three stages, namely connectivity, functionality, and delay. The connectivity test proves that ESP8266 can be connected to Access Points and internet networks, functionality tests prove that sensors can read gas, temperature and humidity and retrieve data. And lastly is testing delay, which is counting the length of the process from the beginning of sensor reading to data up to Firebase's Internet of Things (IoT) -based web. From the results of calculations that have been done in testing, it was found that the time needed for one shipment takes as much as 5-19 seconds. Of course, this time can change because there are aspects that can inhibit internet connection, the number of devices connected to an internet network, but the purpose of this research has been completed with what was expected. Keywords : Hazardous Gas, Temperature and Humidity, Gas Sensors and Temperature and Humidity Sensors, Firebase.

Analysis of climate of Rivnenskyi Nature Reserve from 2000 to 2015

The analysis of monthly climatic terms of Rivnenskyi Nature Reserve was conducted. It is marked that weather terms have substantial differences due to an unstable temperature condition since creation of reserve. A spring period was the shortest in 2013 – 64 days and had the greatest average daily temperature 11.9 °С. Protracted a spring period was in 2002 – 123 days. The most of precipitations in a spring period was fixed in 2008 – 196.2 mm, and the least in 2011 – 42.1 mm. A summer period in 2015 became the most protracted – 131 day. Moreover, the least protracted summer was in 2006 – 90 days. The warmest summer season was in 2010 with an average daily temperature 19.8 °С. The most raining summer was in 2007 when a 471.3 mm of precipitations is fixed, and the least raining summer was in 2002 (144.6 mm of precipitations). The most protracted autumn period was in 2006 – 107 days and the shortest one was in 2001 – 57 days. The warmest autumn was in 2004 when an average daily temperature reached 9.2°С. The most of precipitations in the autumn period is fixed in 2009 – 178 mm, and the least in 2001 – 39 mm. The winter periods were protracted in 2004/05 and 2005/06. Their duration was 114 days. Winter period in 2009/10 with an average daily temperature -7.9°С was the coldest one. The most precipitations are fixed in winter 2005/06 – 208.4 mm, and the least in a winter period 2012/13 are a 52.2 mm. The most of precipitations for a year fell out 777.8 mm in 2012, and the least one in 2011 – 427 mm. The average long-term dates of the beginning of the year seasons are defined. The average long-term date of the beginning of the spring season is on February 27; the summer season is on May 26; the autumn season is on September 14; the winter season is on December 5. Key words: Rivnenskyi Nature Reserve, seasons of the year, precipitation, climatic terms, temperature, long-term date.

Numerical analysis of the coupling between frictionally excited thermoelastic instability and thermal buckling in automotive clutches

The coupling between thermal buckling and thermoelastic instability in clutch disks is investigated using a series of finite element analyses. The temperature distributions are first obtained from the eigenmodes based on the classical thermoelastic instability analyses. The critical buckling temperatures along with the buckling deformation modes of the clutch disk under prescribed temperature fields are subsequently computed using the commercial finite element software ABAQUS. The effects of multiple parameters including sliding speed, coefficient of friction and boundary conditions have been investigated. It is concluded that there exists a strong coupling between thermoelastic instability and thermal buckling, and that the thermoelastic instability induced unstable temperature modes can significantly alter the input temperature profiles for thermal buckling, and thus the critical buckling temperatures. In addition to the effects of axisymmetric thermoelastic instability modes (i.e. banding modes), thermal buckling induced by the nonaxisymmetric thermoelastic instability modes (i.e. focal hot spots) is also tentatively studied.

Viability of Lactobacillus acidophilus NCFM Howaru Dophilus during storage at refrigeration temperatures

A strain Lactobacillus acidophilus NCFM Howaru Dophilus is a probiotic bacterium available in dairy products and dietary supplements since 1970s. Its positive health effects have been proved by many studies. This work deals with the examination of NCFM strain’s viability during its storage at stable and unstable temperature in MRS broth and ultra-pasteurized milk. In nutritionally rich environment, Lb. acidophilus NCFM was able to survive and to metabolize the media. The relevant decrease of viable cells was observed in MRS broth about 30 days after inoculation, and in milk after 21 to 45 days at both stable and unstable temperatures, respectively. The average rate of decrease of viable cells was approximately two to three times higher in experiments at unstable temperature (GrMRS,unst = −0.149 log CFU.ml−1.d−1 in MRS broth, Grmilk,unst = 0.030 log CFU.ml−1.d−1 in milk) compared with that at stable temperature (GrMRS,st = −0.079 log CFU.ml−1.d−1 in MRS broth, Grmilk,st = 0.009 log CFU.ml−1.d−1 in milk). In the MRS broth exhausted by overnight cultivation of NCFM strain the decrease of viable cells started practically immediately (Grovernigh,unst = −0.137 log CFU.ml−1.d−1). Maintenance of the culture in milk at stable temperature was proved to be the most appropriate form of its storage.