Optical Absorption of a D2+ Artificial Molecule Confined in a Spherical Quantum Dot

In this work, we have performed a theoretically study on the energy spectrum, binding energy and intersubband optical absorption of a D2+ complex confined in a spherical quantum dot with finite confinement potential by using diagonalization method within the effective mass approximation. We analyzed the effect of the quantum dot size and internuclear distance on the binding energy, equilibrium distance and optical response of the singly ionized double donor complex. Theoretical analysis of the D2+ system indicated that the internuclear distance significantly affects the energy difference between the two lowest-lying electron states and amplitude of the optical absorption. In general, we conclude that the internuclear distance and quantum dot size dependence of the low-lying energy spectrum of the D2+ complex in a quantum dot favors the describing of an appropriate two-level system needed for quantum computation.

Identification of Track Stability Model Parameters Based on Numerical Experiments

In the article, an identification method of railway track stability model parameters based on energy equilibrium is presented by the authors. A study of two parameters directly influencing the continuous welded track (CWR) stability is described by the authors, i.e., the rail-sleeper structure stiffness Bz is considered one beam, and the ballast lateral resistance r0. These parameters were estimated with the use of a numerical model for various railway track types. The adopted concept is based on the assumption that it is possible to determine substitute values for both parameters. Therefore, using one value of both of these parameters, we label them substitute parameters. The assumed numerical model forced lateral displacements of a track section, and, based on the obtained track section displacement results, energy equilibrium was determined. The equilibrium takes into account the work of external load and the bending work of rail-sleeper structure with the substitute stiffness Bz and the ballast deformation work, also with the substitute value of lateral resistance r0 with lateral displacement. The aim is to identify these substitute values to be used for analysing track stability with the semi-analytical model. These analyses are part of the studies related to the development of a method of assessing various methods of increasing track stability.

Modifikasi Kotak Polistiren untuk Penyimpanan Dingin Sayur Kubis dengan Menggunakan Es Kering sebagai Media Pendingin

ABSTRAK Penelitian telah dilakukan pada kotak modifypolystyrene sebagai kotak pengiriman kubis segar menggunakan es kering sebagai media pendingin. Penelitian ini bertujuan untuk menguji kotak yang dimodifikasi untuk mengetahui kotak yang paling cocok dimodifikasi untuk menjaga kesegaran sayuran. Kotak polystyrene yang dimodifikasi dibuat dengan memisahkan kotak menjadi dua kompartemen, satu kompartemen untuk menempatkan es kering sebagai media pendingin, dan kompartemen lain untuk menyimpan kubis segar. Itu dibuat lima jenis kotak dimodifikasi, dua jenis media pendinginan mondar-mandir di bawah sayuran segar, sedangkan jenis sisanya menempatkan media pendingin di atas sayuran. Tes yang dilakukan selama 7 jam terdiri dari suhu di sekitar kotak, suhu di dalam kotak, dan suhu pusat kubis segar. Pengukuran lain yang dilakukan adalah berat es kering yang digunakan selama penyimpanan dingin, penurunan berat kubis segar, pengamatan visual kerusakan kubis segar, dan perhitungan keseimbangan energi. Menempatkan es kering di bawah kubis segar menyebabkan suhu tengah kubis segar jauh di atas suhu penyimpanan yang disarankan, 0oC, sementara menempatkan media pendingin di atas sayuran memberi dampak negatif pada sayuran di mana suhu tengah kubis segar di bawah 0oC untuk dua jenis kotak yang dimodifikasi, kecuali es kering yang ditempatkan di baskom yang terbuat dari piring zink. Berdasarkan perhitungan energi, terungkap bahwa hampir lebih dari 75% energi pendingin digunakan untuk mengatasi beban pendinginan di sekitarnya. Ditemukan bahwa kotak modifikasi yang paling cocok untuk menyimpan kubis segar adalah jenis kelima. ABSTRACT Research had been carried out to modify polystyrene box as fresh cabbage delivery box using dry ice as a cooling medium. The research aims were to find out the most suitable model box to maintain the freshness of the vegetables. Modified polystyrene box was made by separating the box into two compartments, one compartment for placing dry ice, and another compartment for storing the fresh cabbage. The box was modified into five types which consisted of two types of the box where the cooling medium was placed below the fresh vegetable, while for the rest, the cooling medium was placed above the vegetable. The tests were performed for 7 hours with the hourly observation that consisted of the temperature surrounding the model box, temperature inside the box, and temperature of the center of the fresh cabbage. Other conducted measurements were the weight of dry ice used during cold storage, weight loss of fresh cabbage, visual observation on the deterioration of the fresh cabbage, and energy equilibrium calculation. Placing dry ice below the fresh cabbage caused the center temperature of the fresh cabbage to far above the recommended storing temperature, 0oC, while placing the cooling medium above the vegetable gave a negative impact on the vegetable where the center temperature of the fresh cabbage was below 0oC for the two types of model boxes, except for the fifth type box where dry ice was placed in a basin made of zink plate. Based on energy calculation it was revealed that almost more than 75% of cooling energy was used to overcome the surrounding cooling load. It was found that the most suitable model box for storing the fresh cabbage was the fifth type.

Rotational Flocking with Spontaneous Directional Changes

Revealing the underlying decision-making strategy governing the high-group polarization accompanied by conflicting individual preferences may play a central part in the lives of social animals. Hereby, we construct a structured spin model in accordance with empirical validation, which shows how distinct individual preferences converge from one consensus homeostasis to another lowest-energy equilibrium. To verify the theoretical derivation, we use high-resolution spatiotemporal GPS data of a flock of thirty pigeons and study the dynamical evolution mechanism of systemic spins. Therein, we find successful rotational direction transitions requiring a sufficient number of supporters. A few initiators trigger the phase transition from one equilibrium to another, where the symmetric transient state indicates a diamond hierarchical network being completed by the intermediates and the rear individuals. By further studying the nature, we reveal that decision-making sequences are strongly triggered and influenced by individual positions and the leader-follower relationship. Thus, we can predict which individual is more likely to make the decision before the initial transition moment and who will draw the complete stop. Consequently, the revealed decision-making strategy facilitates a comprehensive understanding of collective behavioral transition.

A metafluid with multistable density and internal energy states

The efficiency, operation range, and environmental safety of energy and refrigeration cycles are determined by the thermodynamic properties of available fluids. We here suggest combining gas, liquid and multistable elastic capsules to create an artificial fluid with a multitude of stable states. We study, theoretically and experimentally, the suspension’s internal energy, equilibrium pressure-density relations and their stability for both adiabatic and isothermal processes. We show that the elastic multistability of the capsules endows the fluid with multistable thermodynamic properties, including the ability of capturing and storing energy at standard atmospheric conditions, not found in naturally available fluids.

Extrusion of stiffening ribs on body parts with local heating

A scheme is proposed and analytical expressions are obtained for calculating the kinematics, pressure and damageability of the material during hot extrusion of ribs on body parts. The equations of states during creep, energy equilibrium, kinetics of material discontinuity are used. The calculation results are presented. Keywords: extrusion, local heating, stiffening rib, viscosity, plasticity, stress relaxation, pressure, velocity field [email protected], [email protected]

Multi-Period Transportation Equilibrium Approach For Transportation Planning

Previous studies in transportation equilibrium have focused on models in which travel demands were functions of travel time in the current time period. Most of these models are single-period models, neglecting the time lag effect. However, the time lag effect can be a very important factor, especially in long-term transportation planning. In this thesis the geometric distributed lag (GDL) structure used in energy equilibrium models is applied to the multi-period transportation equilibrium models.

Multi-Period Transportation Equilibrium Approach For Transportation Planning

Previous studies in transportation equilibrium have focused on models in which travel demands were functions of travel time in the current time period. Most of these models are single-period models, neglecting the time lag effect. However, the time lag effect can be a very important factor, especially in long-term transportation planning. In this thesis the geometric distributed lag (GDL) structure used in energy equilibrium models is applied to the multi-period transportation equilibrium models.