Mpemba Effect- the Effect of Time

This paper draws the following conclusions on the nature of time by analyzing the relationship between time and speed, the relationship between time and gravitational field, the gravitational redshift of the photon, and the black-body radiation theorem: Time on an object is proportional to the amount of energy flowing out (or in) per unit time (observer’s time) per unit surface area of the object. When an object radiates energy outward: t'=μB(T) =μσT 4=μnhν/st Where t’ is the time on the object, μ is a constant, B(T) is the radiosity，the total energy radiated from the unit surface area of the object in unit time (observer’s time), σ is the Stefan-Boltzmann constant, T is the absolute temperature, n is the number of the photons radiated, ν is the average frequency of the photons radiated, s is the surface area of the object and t is the time on the observer. When the object radiates energy outward, the higher the energy density of the space (for example the stronger the gravitational field of the space), the smaller the radiosity B(T) of the object in the space, the longer the average wavelength of the light quantum emitted by the object, the slower the time on the object, the longer the life of the system. When the object radiates energy outward, the faster the object moves relative to the ether, the higher the energy density of the local space in which the object is located, the smaller the radiosity B(T) of the object, the longer the average wavelength of the light quantum radiated by the object, the slower the time on the object, and the longer the life of the system. When the object radiates energy outward, the higher the temperature of the object, the greater the object's radiosity B(T), the shorter the average wavelength of the light quantum radiated by the object, the faster the time on the object, and the shorter the life of the system. Applying the above conclusions about the nature of time, the author analyzes the Mpemba effect and the inverse Mpemba effect, and reaches the following conclusion: the Mpemba effect is the time effect produced when heat flows from objects into space, and the "inverse" Mpemba effect is the time effect produced when heat flows from space into objects.

A Review on Gas-Liquid Mass Transfer Coefficients in Packed-Bed Columns

This review provides a thorough analysis of the most famous mass transfer models for random and structured packed-bed columns used in absorption/stripping and distillation processes, providing a detailed description of the equations to calculate the mass transfer parameters, i.e., gas-side coefficient per unit surface ky [kmol·m−2·s−1], liquid-side coefficient per unit surface kx [kmol·m−2·s−1], interfacial packing area ae [m2·m−3], which constitute the ingredients to assess the mass transfer rate of packed-bed columns. The models have been reported in the original form provided by the authors together with the geometric and model fitting parameters published in several papers to allow their adaptation to packings different from those covered in the original papers. Although the work is focused on a collection of carefully described and ready-to-use equations, we have tried to underline the criticalities behind these models, which mostly rely on the assessment of fluid-dynamics parameters such as liquid film thickness, liquid hold-up and interfacial area, or the real liquid paths or any mal-distributions flow. To this end, the paper reviewed novel experimental and simulation approaches aimed to better describe the gas-liquid multiphase flow dynamics in packed-bed column, e.g., by using optical technologies (tomography) or CFD simulations. While the results of these studies may not be easily extended to full-scale columns, the improved estimation of the main fluid-dynamic parameters will provide a more accurate modelling correlation of liquid-gas mass transfer phenomena in packed columns.

Jointed Plain Concrete Pavements in Airports: Structural–Economic Evaluation and Proposal for a Catalogue

Although the design of jointed plain concrete pavements could be solved by commercial software, there is still a need for simple tools to be used in feasibility studies and preliminary cost–benefit analyses. This paper analyzed and verified jointed plain concrete pavements for airports composed of square slabs without tie and dowel bars. The examined slabs are laid on a cement-treated base layer and a stabilized granular subbase layer. The finite element software FAARFIELD was used to design the JPCP pavements when they are subjected to the design of the airplane (i.e., turboprop C-130J Hercules) under different conditions. Seven subgrade load bearing capacity values, twenty traffic levels, and two construction hypotheses (i.e., constant or variable thickness of the two deeper layers) were designed and then verified with the Westergaard theory in order to present a proposal for a catalogue. Finally, the construction cost per unit surface area was calculated for different construction methods of paving (by slip form paver or by fixed form). The obtained results provide a simple and fast procedure to design preliminary airport JPCPs.

OBTAINING BIODEGRADABLE COMPOSITE MATERIALS BASED ON POLYOLEFINS AND HUSK OF SUNFLOWER SEEDS

The paper presents the results of a comparative study of physical and mechanical, rheological, and biodegradable characteristics of a mixture containing low- and high-pressure polyethylene (HDPE 273-83 and HDPE 15303-003, respectively) in a 1:1 ratio filled with finely ground (less than 200 microns) sunflower husk (5-30% by weight). The mixture also contained 10% compatibilizer (functionalized by the method of alkaline alcoholysis of sevilen (SEVA 12206-007) and 1% of technological additive (polyethylene glycol (PEG-115 (4000). It has been established that as the content of the plant filler increases (up to 25%), the elastic modulus and tensile strength has not practically changed. The relative elongation of the composite under tension exceeds 100% (with a sunflower husk content up to 15% by weight). The complex viscosity and shear modulus of the considered melts with different filler contents are almost at the same level. The introduction of sunflower husk (up to 30%) and compatibilizer (10%) helps to reduce the viscosity and elasticity of the melts, which is evidence of a significant improvement in the processability of the compositions compared to HDPE 273-83. For a comparative assessment of composites biodegradability, moisture absorption, chemical oxygen consumption, and composites mass loss in laboratory soil during exposure for 12 months were being studied. It is shown that with increasing filler content, the ability of composites to biodegradation increases. In addition, it was found that the indicator of chemical oxygen consumption per unit surface area of the sample is a more productive and reproducible estimate in comparison with traditional methods for assessing the degradability of composite materials.

The Role of Leadership on Emotion Regulation, Service Delivery, and Health: A Multi-Level Study

Prior research on emotional labor has primarily been conducted at the individual level. In this paper, we examine a model of unit employee emotional labor and its relationships with unit LMX and LMX differentiation as well as with unit employee outcomes. Results from 701 employees and 117 managers from 117 branches of a real-estate company in Taiwan showed that deep acting exhibited a higher consistency and agreement at the unit level than surface acting. Further, we found that unit LMX was positively related to unit employee deep acting, and that LMX differentiation moderated the effect of unit LMX on surface acting in such a way that the relationship was more negative when LMX differentiation was high. In addition, unit surface acting was negatively related to supervisor-rated employee customer-oriented behavior and positively related to employee somatic symptoms.

K-Modified Co–Mn–Al Mixed Oxide—Effect of Calcination Temperature on N2O Conversion in the Presence of H2O and NOx

The effect of calcination temperature (500–700 °C) on physico-chemical properties and catalytic activity of 2 wt. % K/Co-Mn-Al mixed oxide for N2O decomposition was investigated. Catalysts were characterized by inductively coupled plasma spectroscopy (ICP), X-ray powder diffraction (XRD), temperature-programmed reduction by hydrogen (TPR-H2), temperature-programmed desorption of CO2 (TPD-CO2), temperature-programmed desorption of NO (TPD-NO), X-ray photoelectron spectrometry (XPS) and N2 physisorption. It was found that the increase in calcination temperature caused gradual crystallization of Co-Mn-Al mixed oxide, which manifested itself in the decrease in Co2+/Co3+ and Mn3+/Mn4+ surface molar ratio, the increase in mean crystallite size leading to lowering of specific surface area and poorer reducibility. Higher surface K content normalized per unit surface led to the increase in surface basicity and adsorbed NO per unit surface. The effect of calcination temperature on catalytic activity was significant mainly in the presence of NOx, as the optimal calcination temperature of 500 °C is necessary to ensure sufficient low surface basicity, leading to the highest catalytic activity. Observed NO inhibition was caused by the formation of surface mononitrosyl species bonded to tetrahedral metal sites or nitrite species, which are stable at reaction temperatures up to 450 °C and block active sites for N2O decomposition.

Ferrofluid thin films for aerofoil lift enhancement and delaying flow separation

ABSTRACTIn this work, consideration is given to a novel concept for aerofoil lift enhancement and delaying flow separation. Here, lift enhancement is attained by preventing the growth of the boundary layer through the elimination of the zero-slip condition between the wing surface and the air stream. The concept would simulate all the effects of a moving wall, leading to the appearance of a slip velocity at the gas–fluid interface, including the injection of momentum into the air boundary layer, but with one exception: here there is no moving wall but instead a ferrofluid thin film pumped parallel and attached to the wall by a magnetic field. Utilising a simplified physical model for the velocity profile of the ferrofluid film and based on ferrohydrodynamic stability considerations, an analytical expression for the interfacial velocity is derived. Finally, from the available experimental data on moving walls, the expected lift and angle-of-attack enhancement are found as well as the weight penalty per unit surface area of the wing is estimated. Additional research and development is required to explore the possibilities of using ferrofluid thin films.

Numerical Study on the Influence Mechanism of Crosswind on Frozen Phenomena in a Direct Air-Cooled System

The frozen phenomenon is unfavorable for the direct air-cooled condensers (DACCs) in a very cold area. The effect of crosswind on frozen phenomena in DACCs at the representative 2 × 350 MW thermal power units was investigated numerically. Results showed that when the crosswind velocity was 4 m·s−1, the number of frozen air-cooled units reached a maximum of six. The increase of vortex range in the air-cooled unit was one of the important reasons to restrain the formation of frozen phenomena at a crosswind velocity from 4 m·s−1 to 12 m·s−1. The frozen phenomena in the DACC disappeared when the crosswind velocity was 12 m·s−1. As the crosswind velocity continued to increase to 28 m·s−1, the frozen region mainly appeared at the position of column 1 row 4, where the airflow rate was the maximum and the inlet air temperature was the minimum among all air-cooled units. This phenomenon occurred because there existed a relatively high-pressure zone near the inlet of each frozen air-cooled unit. In addition, although the frozen area increased from one-third of the air-cooled unit surface to half with the crosswind velocity from 20 m·s−1 to 28 m·s−1, the flow characteristics and the size of vortices in the air-cooled unit were similar in the above two crosswind conditions. Therefore, the key influencing factor became the airflow rate and the inlet air temperature of the air-cooled units under strong crosswind conditions. This study has important guiding significance for the antifreezing design and operation of DACCs.

PENGARUH KEKUATAN DAN KEKERASAN BATUAN TERHADAP PRODUKTIVITAS SURFACE MINER DI PT. SEMEN BATURAJA (PERSERO) TBK

Surface Miner digunakan oleh SMBR untuk mengoptimalkan pengambilan material batugamping pada area-area yang berdekatan dengan pemukiman penduduk dimana kegiatan peledakan sudah dibatasi. Tujuan penelitian untuk melakukan klasifikasi nilai kekuatan dan kekerasan batugamping pada area kerja surface miner di SMBR, menganalisis pengaruh nilai kekuatan dan kekerasan batugamping terhadap produktivitas unit surface miner di SMBR, membandingkan biaya akibat pengaruh nilai kekuatan dan kekerasan terhadap penggunaan cutting tools, fuel, dan jam kerja surface miner pada area kerja surface miner. Data primer terdiri dari data produktivitas alat surface miner, data penggunaan bahan bakar/fuel. Data sekunder terdiri dari data geoteknik khususnya data kekuatan batuan (UCS), data nilai kekerasan batuan, data pengujian kualitas kimia (SiO2) dan serta sifat fisik dan mekanik batugamping. Batugamping yang diamati memiliki sifat fisik dan mekanik serta kandungan silika pada batugamping tersebut. Sifat fisik batugamping berupa densitas batuan antara 1,79 gr/cm3 sd 2,53 gr/cm3, sifat mekanik berupa UCS antara 1,42 mpa sd 104,55 mpa, sedangkan kandungan silika antara 0,75 % sd 88,52 %. Batugamping pada area kerja surface miner di klasifikasikan menjadi tiga berdasarkan data kekuatan dan kekerasan batuan, berupa zona batuan kuat sedang- keras, zona batuan tidak kuat – tidak keras, dan zona batuan sangat tidak kuat-tidak keras.

Effect of Polishing Brick Powder on Mortar Sorptivity and its Mechanism

In this study, the effect of polishing brick powder replacement cement slurry method on water absorption of motar is discussed. A series of mortar samples are prepared for testing water penetration amount at unit surface area with square of time and permeable porosity. The results show that the replacement of cement slurry with polished brick powder will increase the permeable pore of mortar and increase the sorptivity per unit area, thus effectively reducing the sorptivity of mortar at the same water cement ratio or strength.