DESIGN OF A MICROSTRIP FILTER FOR MICROWAVE POINT-TO-POINT LINK

The goal of the project is to design a Microstrip Bandpass filter for a point-to-point exchange of information over the microwave-frequency signals. Thus, the main idea of this project is to design a bandpass Chebyshev-type 1 filter using a Microstrip as a transmission line. The biggest obstacle for the project is to have a high performance or in other words a high quality response using a Microstrip transmission line. The scope of the project embraces the understanding and application of techniques for designs of microwave filters, which takes us back to the two-port networks, transmission lines, bandpass filters and microwave communications with enabling us to make more research on the mentioned areas. The design was simulated on MATLAB and a 7th order Chebyshev type 1 filter response was generated. After the design calculations were done, it was simulated, tuned and optimized on AWR Microwave Office, simulation software for better approximations, where we could analyze the response of the filter. The AWR simulation software showed an almost equiripple response with 7 ripples, which concludes that the design was successful

Addressing Challenges of Dryland Production of Sunflowers and Corn in the Semi-Arid High Plains of Nebraska

Corn and sunflower are value crops for America. Cultivation of corn and sunflower often vary depending on growing environment. Selecting appropriate planting dates, hybrids and plant density frequently concerns farmers. This concern is understandable because the decision made directly impacts final income. The objectives were to evaluate interaction of corn and sunflower planting dates and hybrid maturity and evaluate interaction of corn flex hybrids and plant density under conditions of western Nebraska. Nine corn hybrids with relative maturity ranging from 86 to 105 days were sown between early May and late June in first and between late April and early June in second year of study at the High Plains Agricultural Laboratory near Sidney NE in 2021 to 2022. The optimal planting date to achieve maximum grain yield was early May in the first year and over 50% decrease of grain yield was observed when planting date was delayed from early May to late June. In the second-year planting dates had no significant variation in terms of grain yield while corn planted later than May failed to yield. Variation among hybrids in terms of grain yield was not significant in 2021 while in 2022 hybrid NK 0440 had an 85% decrease in yield in contrast to DKC 36-86 RIB. Three sunflower hybrids with relative maturities of 89, 94 and 98 days were sown between 9 May and 24 June at the High Plains Agricultural Laboratory near Sidney NE in 2021 to 2022. Sunflower planted in early May achieved maximum grain yield and 64% decrease of grain yield occurred when planting date was delayed from early May to late May. Early maturing hybrid averaged across all planting dates indicated 70 percent greater grain yield than the medium maturity hybrid. Four corn hybrids with different ear flex characteristics were planted at 19,768; 27,181; 34,595; 42,007; and 49,420 plants per hectare populations in Nebraska, one near Sidney and the other in Box Butte County from 2021-2022. A plant population of 34,595 achieved greatest grain yield in 2021. When population was increased from 34,595 to 42,007 grain yield decline on 12% was observed. In 2022, grain yield varied significantly by hybrids. Hybrids CP 3337 and DKC 42-04 RIB had greatest grain yield of 2,295 and 2,271 kilograms per hectare. CP 3337 produced in average 32 percent secondary ears greater than all hybrids. Advisors: Cody F. Creech and Amanda C. Easterl

Realization of Green Engineering at ETUT

Despite being one of the young universities in the country, Oguz han Engineering and technology university of Turkmenistan (ETUT) aims to integrate all sustainable development goals in all aspects of its education and research programs within the scope of “Green Engineering." To increase the awareness and recognition of green engineering in our university, community, country, and world, we are developing sustainable projects such as the production of green hydrogen through solar panels, conversion of plastic waste into liquid fuel, bioethanol production from cotton stalks, sorting of solid wastes with a novel waste separator, production of synthetic fibers, clonal propagation of local plants, and obtaining of degradable bioplastics. This paper will explain these projects in detail accordingly. Realization and implementation of these projects into our society will contribute to applying sustainable development goals in the energy, climate change, and waste management areas of campus sustainability.   

Tandem catalysis for the production of alkyl lactates from ketohexoses at moderate temperatures

Retro-aldol reactions have been implicated as the limiting steps in catalytic routes to convert biomass-derived hexoses and pentoses into valuable C_2, C_3, and C_4 products such as glycolic acid, lactic acid, 2-hydroxy-3-butenoic acid, 2,4-dihydroxybutanoic acid, and alkyl esters thereof. Due to a lack of efficient retro-aldol catalysts, most previous investigations of catalytic pathways involving these reactions were conducted at high temperatures (≥160 °C). Here, we report moderate-temperature (around 100 °C) retro-aldol reactions of various hexoses in aqueous and alcoholic media with catalysts traditionally known for their capacity to catalyze 1,2-intramolecular carbon shift (1,2-CS) reactions of aldoses, i.e., various molybdenum oxide and molybdate species, nickel(II) diamine complexes, alkali-exchanged stannosilicate molecular sieves, and amorphous TiO_2–SiO_2 coprecipitates. Solid Lewis acid cocatalysts that are known to catalyze 1,2-intramolecular hydride shift (1,2-HS) reactions that enable the formation of α-hydroxy carboxylic acids from tetroses, trioses, and glycolaldehyde, but cannot readily catalyze retro-aldol reactions of hexoses and pentoses at these moderate temperatures, are shown to be compatible with the aforementioned retro-aldol catalysts. The combination of a distinct retro-aldol catalyst with a 1,2-HS catalyst enables lactic acid and alkyl lactate formation from ketohexoses at moderate temperatures (around 100 °C), with yields comparable to best-reported chemocatalytic examples at high temperature conditions (≥160 °C). The use of moderate temperatures enables numerous desirable features such as lower pressure and significantly less catalyst deactivation

Innovative Approach to Training Sustainable Engineers

Oguz han Engineering and Technology University of Turkmenistan is a higher education institution, which specializes in training engineers with innovative views. Training of future professionals that “Engineer a Sustainable World” requires not only new competencies, including creative learning and thinking, complex problem-solving interdisciplinary and international cooperation, and a code of ethics, but also challenges a change in engineering education itself. In our approach, we suggest innovative ways to develop a deeper working knowledge of technical fundamentals while simultaneously learning personal and interpersonal skills, and product, process, and system building skills. For analysis of interrelated arrangement of modules for effective acquisition of knowledge, a supportive alignment of disciplinary courses was studied and a wide range of skills required in professional areas were mapped throughout the curriculum. Moreover, we created a new learning context that provides an opportunity to implement both theoretical and practical knowledge to conceive, design, implement and operate real-world systems and products. In this approach, we developed integrated methods of gaining active learning experience that forms a basis for carrying out challenging capstone projects. As a result, our innovative approach that focuses on modification of education and research improves all aspects of comprehensive training of sustainable engineers

Development and Characterization of Catalytic Systems for Biomass-Derived Chemical Feedstocks

Heterogeneous catalysis by Brønsted and/or Lewis acid sites isolated within microporous environments is a topic that is perpetually growing in scope and importance. While Brønsted acid sites in zeolites have been studied and applied extensively in the petrochemical industry, new opportunities for green processes based on renewable chemical feedstocks call for applications of new microporous materials that possess Lewis acid sites (e.g., zeotypes with framework Sn, Ti, Zr, or Hf). Characterization of such materials and the specific structures of the Lewis acid sites provides insights for rational catalyst design and application. This work provides experimental evidence for the identities of the active sites in Sn-Beta zeotype for the 1,2-intramolecular hydride shift (1,2-HS) reaction that results in D-glucose isomerization to D-fructose, and for the 1,2-intramolecular carbon shift (1,2-CS) reaction that results in D-glucose isomerization to D-mannose. Specifically, by selective poisoning experiments, the partially-hydrolyzed, "open" Sn site is shown to be the active site for the 1,2-HS reaction. The participation of the proximal silanol of such an open Sn site in the 1,2-HS reaction is demonstrated thorough alkali-exchange experiments. Such experiments also reveal that the active site for the 1,2-CS reaction is an open Sn site with a cation-exchanged proximal silanol. 1,2-CS catalysts, in general, are shown to also catalyze retro-aldol reactions of hexoses at moderate temperatures (ca. 100 °C), and to be compatible with microporous 1,2-HS catalysts in tandem catalytic schemes that enable production of alkyl lactates. Finally, the Lewis acidity of framework Zn in zincosilicate microporous materials is demonstrated through probe-molecule infrared spectroscopy. One such material is then shown to catalyze Diels-Alder cycloaddition-dehydration reactions of oxygenated furans and ethylene. To the best of our knowledge, these materials are the first heterogeneous catalysts reported to catalyze the direct formation of terephthalate esters from ethylene and dimethyl 2,5-furandicarboxylate with appreciable selectivity. </p

Catalysis by framework zinc in silica-based molecular sieves

Microporous and mesoporous zincosilicates (e.g., CIT-6, VPI-8, Zn-MFI, and Zn-MCM-41) synthesized in the presence of alkali cations contain two broad types of Zn sites: one that is a dication analog of the monocation ion-exchangeable Al-site in aluminosilicates, while the other resembles isolated Zn sites on amorphous silica. The ratio of these sites varies, depending on the synthesis conditions of the zincosilicate. Post-synthetic strategies based on ion-exchange can alter the site distribution towards either population. Furthermore, post-synthetic introduction of isolated Zn sites of the latter type is possible for materials possessing silanol nests. Both types of sites behave as Lewis acid centers in probe-molecule IR spectroscopy, but have very different catalytic properties. Due to the unusually high adsorption energies of Lewis bases on such materials, Lewis acid catalysis is difficult at low temperatures and in solvents bearing Lewis basic functionality. However, at high temperatures, in hydrocarbon solvents, CIT-6 (Zn-beta) is able to selectively catalyze the Lewis-acid-catalyzed Diels–Alder cycloaddition–dehydration reactions of ethylene with methyl 5-(methoxymethyl)furan-2-carboxylate, a furan that can be derived quantitatively by partial oxidation of biomass-based 5-hydroxymethylfurfural. Additionally, zinc in silica-based molecular sieves is shown here to enable chemistries previously not accessible with framework Sn-, Ti- and Zr-based Lewis acid sites, e.g., the direct production of dimethyl terephthalate by Diels–Alder cycloaddition–dehydration reactions of ethylene and the dimethyl ester of furan-2,5-dicarboxilic acid

Explicit solution for vibrating bar with viscous boundaries and internal damper

We investigate longitudinal vibrations of a bar subjected to viscous boundary conditions at each end, and an internal damper at an arbitrary point along the bar's length. The system is described by four independent parameters and exhibits a variety of behaviors including rigid motion, super stability/instability and zero damping. The solution is obtained by applying the Laplace transform to the equation of motion and computing the Green's function of the transformed problem. This leads to an unconventional eigenvalue-like problem with the spectral variable in the boundary conditions. The eigenmodes of the problem are necessarily complex-valued and are not orthogonal in the usual inner product. Nonetheless, in generic cases we obtain an explicit eigenmode expansion for the response of the bar to initial conditions and external force. For some special values of parameters the system of eigenmodes may become incomplete, or no non-trivial eigenmodes may exist at all. We thoroughly analyze physical and mathematical reasons for this behavior and explicitly identify the corresponding parameter values. In particular, when no eigenmodes exist, we obtain closed form solutions. Theoretical analysis is complemented by numerical simulations, and analytic solutions are compared to computations using finite elements.Comment: 29 pages, 6 figure

Systematic approach for the test data generation and validation of ISC/ESC detection methods

Various methods published in recent years for reliable detection of battery faults (mainly internal short circuit (ISC)) raise the question of comparability and cross-method evaluation, which cannot yet be answered due to significant differences in training data and boundary conditions. This paper provides a Monte Carlo-like simulation approach to generate a reproducible, comprehensible and large dataset based on an extensive literature search on common assumptions and simulation parameters. In some cases, these assumptions are quite different from field data, as shown by comparison with experimentally determined values. Two relatively simple ISC detection methods are tested on the generated dataset and their performance is evaluated to illustrate the proposed approach. The evaluation of the detection performance by quantitative measures such as the Youden-index shows a high divergence with respect to internal and external parameters such as threshold level and cell-to-cell variations (CtCV), respectively. These results underline the importance of quantitative evaluations based on identical test data. The proposed approach is able to support this task by providing cost-effective test data generation with incorporation of known factors affecting detection quality

ON REPRESENTATION OF ONE CLASS OF SCHMIDT OPERATORS

In this paper, unitary symmetrizers are considered. It is well known that using Newton operatoralgorithm, similar to the usual Newton algorithm, for extracting the square root, one can provethat for every Hermitian operator T 0, there exists a unique Hermitian operator S 0 suchthat T = S2. Moreover, S commutes with every bounded operator R with which commutes T. Theoperator S is called a square root of the operator T and is denoted by T1=2. The existence of thesquare root allows one to determine the absolute value jTj = (TT)1=2 of the bounded operator T.For every bounded linear operator T : H ! H there exists a unique partially isometric operatorU : H ! H such that T = UjTj, KerU = KerT. Such an equality is called a polar expansionof the operator T. The Schmidt operator is understood as the unitary multiplier of the polarexpansion of a compact inverse operator, with the help of which E. Schmidt was the rst to obtainthe expansion of a compact and not-self-adjoint operator and introduced so-called s-numbers.This paper shows that the unitary symmetrizer of an operator diers only in sign from the adjointSchmidt operator. The main result of the paper: if A is an invertible and compact operator, andS is a unitary operator such that the operator SA is self-adjoint, then the operator AS is alsoself-adjoint and the formula S = U holds, where U is the Schmidt operator