Some Problems on the Sectoral Structure, GDP Growth and Sustainability of Vietnam

The Vietnam development has been enjoying a great deal of rapid economic growth in the last decades, which thank to the opening of market-oriented economy system. However, the economic growth is slowly recent years and the increase of environmental issues. The reason for this situation is that misallocation of resource, the sectoral development policies as well as the development orientation of the government. In order to find the solution, this research applies the input output model to analysis the sectoral structure and economic growth as well as the sustainability of economic growth and the effect of economics on the environment. Then, this research recommends the better sectoral structure for Vietnam in order to allocate resources efficiently and forward to the sustainable development.The purpose of this study was to point out the instability of Vietnam, not only for the environment but also for the whole economy. Research shows that VN is not only the face of environmental pollution, but also uncertainty about macroeconomic. It also pointed out the need to change the economic structure for economic development that the environment in a sustainable way. This research based on Leontief and Ghosh system

On three soft rectangle packing problems with guillotine constraints

We investigate how to partition a rectangular region of length $L_1$ and height $L_2$ into $n$ rectangles of given areas $(a_1, \dots, a_n)$ using two-stage guillotine cuts, so as to minimize either (i) the sum of the perimeters, (ii) the largest perimeter, or (iii) the maximum aspect ratio of the rectangles. These problems play an important role in the ongoing Vietnamese land-allocation reform, as well as in the optimization of matrix multiplication algorithms. We show that the first problem can be solved to optimality in $\mathcal{O}(n \log n)$, while the two others are NP-hard. We propose mixed integer programming (MIP) formulations and a binary search-based approach for solving the NP-hard problems. Experimental analyses are conducted to compare the solution approaches in terms of computational efficiency and solution quality, for different objectives

Optical engineering of iii-nitride nanowire light-emitting diodes and applications

Applications of III-nitride nanowires are intensively explored in different emerging technologies including light-emitting diodes (LEDs), laser diodes, photodiodes, biosensors, and solar cells. The synthesis of the III-nitride nanowires by molecular beam epitaxy (MBE) is investigated with significant achievements. III-nitride nanowires can be grown on dissimilar substrates i.e., silicon with nearly dislocation free due to the effective strain relaxation. III-nitride nanowires, therefore, are perfectly suited for high performance light emitters for cost-effective fabrication of the advanced photonic-electronic integrated platforms. This dissertation addresses the design, fabrication, and characterization of III-nitride nanowire full-color micro-LED (µLED) on silicon substrates for µLED display technologies, high-efficient ultraviolet (UV) LEDs, and spectral engineering for narrow band LEDs. In this dissertation, InGaN/AlGaN nanowire µLEDs were demonstrated with highly stable emission which can be varied from the blue to red spectrum. Additionally, by integrating full-color emissions in a single nanowire, phosphor-free white-color µLEDs are achieved with an unprecedentedly high color rendering index of ~ 94. Such high-performance µLEDs are perfectly suitable for the next generation high-resolution micro-display applications. Moreover, the first demonstration of two-step surface passivation using Potassium Hydroxide (KOH) and Ammonium Sulfide (NH4)2Sx is reported. The photoluminescence, electroluminescence, and optical power of the 335 nm AlGaN nanowire UV LEDs show improvements by 49%, 83%, and 65%, respectively. Such enhanced performance is attributed to the mitigation of the surface nonradiative recombination on the nanowire surfaces. A combination of KOH and (NH4)2Sx treatment shows a promising approach for high efficiency and high power AlGaN nanowire UV LEDs. The LEDs with narrow spectra are highly desirable light sources for precisely controlled applications such as phototherapy. In this regard, we have further demonstrated narrow spectral nanowire LEDs using on-chip integrated bandpass filters. To achieve narrow band spectra, the bandpass filters are designed and fabricated using all-dielectric and metal-dielectric multilayers for visible and UV regions, respectively. They are fabricated onto LED devices as a single photonic platform to achieve the narrow band LEDs for innovative applications like phototherapy for wound healing

A stochastic model of the influence of buffer gas collisions on Mollow spectra

In this paper we consider the influence of collisional fluctuations on the Mollow spectra of resonance fluorescence (RF). The fluctuations are taken into account by a simple shift of the constant detuning, involved in a set of optical Bloch equations by collision frequency noise which is modelled by a two-step random telegraph signal (RTS). We consider in detail the Mollow spectra for RF in the case of an arbitrary detuning of the laser frequency, where the emitter is a member of a statistical ensemble in thermodynamic equilibrium with the buffer gas at temperature $T$ which is treated as a colored environment, and velocity $v$ is distributed with the Maxwell-Boltzmann density

Failure of rammed earth walls: from observations to quantifications

International audienceNowadays, rammed earth construction is attracting renewed interest throughout the world thanks to its "green" characteristics in the context of sustainable development. Firstly, using a local material (soil on site or near the site), rammed earth constructions have very low embodied energy. Secondly, rammed earth houses have an attractive appearance and present advantageous living comfort due to substantial thermal inertia and the "natural regulator of moisture" of rammed earth walls. This is why several research studies have been carried out recently to study the mechanical and thermal characteristics of rammed earth. However, to our knowledge, there are not yet sufficient studies on the tensile strength and the shear strength of rammed earth. The tensile strength of rammed earth is neglected in general due to its very low value, but in extreme conditions (e.g., seismic conditions), knowing the tensile strength is necessary for structural design. Moreover, the shear strength is required in many cases to check the local failure of rammed earth quickly, which has been observed in old structures (especially those submitted to concentrated loads). This paper presents experimental results on tensile strengths and the Poisson ratio of rammed earth specimens. Local failure tests were also conducted on 1 m × 1 m × 0.3 m wallettes manufactured in the laboratory. The shear strength was then identified using a simple method based on compressive strength, tensile strength and Mohr's circle theory. The approach proposed was validated by tests on the wallettes. Finite Element (FE) modeling was also carried out to confirm the results. Last, the method presented was validated for stabilized rammed earth lintels presented in the literature

Computer On-Demand Architecture (CODArc)

This paper proposes a new computer architecture that is designed to be specifically lean and secure. Due to recent advances in network speeds which allow users to pull data from the internet just as fast as from local hard drive, this architecture forgoes the typical arrangement of computers and sources its hard disk data from the cloud. On the local hardware, the MMU is removed and local peripherals are implemented on an FPGA to be swapped out when not in use. We have completed most of the high-level design of the system, and have prototyped a suitable data server; however, the local software and hardware will need to be further developed for this architecture to be complete

Modelling and solving complex combinatorial optimization problems : quorumcast routing, elementary shortest path, elementary longest path and agricultural land allocation

The feasible solution set of a Combinatorial Optimization Problem (COP) is discrete and finite. Solving a COP is to find optimal solutions in the set of feasible solutions such that the value of a given cost function is minimized or maximized. In the literature, there exist both complete and incomplete methods for solving COPs. The complete (or exact) methods return the optimal solutions with the proof of the optimality, for example the branch-and-cut search. The incomplete methods try to find hight-quality solutions which are as close to the optimal solutions as possible, for example local search. In this thesis we focus on solving four distinct COPs: the Quorumcast Routing Problem (QRP), the Elementary Shortest Path Problem on graphs with negative-cost cycles (ESPP), the Elementary Longest Path Problem on graphs with positive-cost cycles (ELPP), and the Agricultural Land Allocation Problem (ALAP). In order to solve these problems with the complete methods, we use the Branch-and-Infer search, the Branch-and-Cut search, and the Branch-and-Price search. We also solve ALAP by the incomplete methods, such as Local Search, Tabu Search, Constraints-Based Local Search that combine with metaheuristics. The experimental evaluations on well-known benchmarks show that all proposed algorithms for all the first three COPs (QRP, ESPP and ELPP) are better than the-state-the art algorithms. Specially, we describe ALAP, formulate it as a combination of three COPs, and propose several complete and incomplete algorithms for these COPs.(FSA - Sciences de l'ingénieur) -- UCL, 201

Comparison of Investment Platforms and Exchanges for Cryptocurrency Trading

Bakalářská práce je zaměřena investiční platformy a burzy pro obchodování s kryptoměnami. Cílem práce je zvolit nejlepší variantu platformy či burzy pro předem definovaného klienta za pomocí metod vícekriteriální hodnocení variant. Teoretická část zahrnuje základní pojmy ze světa kryptoměn. V následující části je popsána metodika vícekriteriálního rozhodování a jsou zmíněny zvolené metody. Praktická část obsahuje definici pojmu krypto-burza, dále jsou představeny platformy a burzy, varianty řešení a předem stanovená rozhodovací kritéria. Závěrečná část je věnována konečnému hodnocení a určení nejvhodnější platformy či burzy pro předem definovaného klienta. Výsledky tohoto hodnocení jsou založeny na základě subjektivních preferencí rozhodovatele, a proto nejsou doporučeny k dalšímu použití.The bachelor thesis focuses on investment platforms and exchanges for cryptocurrency trading. The aim of the thesis is to select the best variant of the platform or exchange for a predefined client using methods of multi-criteria decision analysis. The theoretical part includes basic concepts from the world of cryptocurrencies. In the following section, the methodology of multi-criteria decision making is described and the chosen methods are mentioned. The practical part includes the definition of the term crypto-exchange, then platforms and exchanges, solution variants and predefined decision criteria are presented. The final part is devoted to the final evaluation and determination of the most suitable platform or exchange for a predefined client. The results of this evaluation are based on the subjective preferences of the decision maker and are therefore not recommended for further use.154 - Katedra financívelmi dobř