Challenges and opportunities in the production of magnesium parts by directed energy deposition processes

Mg-alloys have gained considerable attention in recent years for their outstanding properties such as lightweight,high specific strength,and corrosion resistance,making them attractive for applications in medical,aerospace,automotive,and other transport industries.However,their widespread application is hindered by their low formability at room temperature due to limited slip systems.Cast Mg-alloys have low mechanical properties due to the presence of casting defects such as porosity and anisotropy in addition to the high scrap.While casting methods benefit from established process optimization techniques for these problems,additive manufacturing methods are increasingly replacing casting methods in Mg alloys as they provide more precise control over the microstructure and allow specific grain orientations,potentially enabling easier optimization of anisotropy properties in certain applications.Although metal additive manufacturing(MAM)technology also results in some manufacturing defects such as inhomogeneous microstructural evolution and porosity and additively manufactured Mg alloy parts exhibit lower properties than the wrought parts,they in general exhibit superior properties than the cast counterparts.Thus,MAM is a promising technique to produce Mg alloy parts.Directed energy deposition processes,particularly wire arc directed energy deposition(WA-DED),have emerged as an advantageous additive manufacturing(AM)technique for metallic materials including magnesium alloys,offering advantages such as high deposition rates,improved material efficiency,and reduced production costs compared to subtractive processes.However,the inherent challenges associated with magnesium,such as its high reactivity and susceptibility to oxidation,pose unique hurdles in the application of this technology.This review paper delves into the progress made in the application of DED technology to Mg-alloys,its challenges,and prospects.Furthermore,the predominant imperfections,notably inhomogeneous microstructure evolution and porosity,observed in Mg-alloy components manufactured through DED are discussed.Additionally,the preventive measures implemented to counteract the formation of these defects are explored.

紫外光直接光氧化浸出铜渣

采用光化学反应研究了铜渣中Cu和Fe的溶解行为。实验采用石英玻璃夹套,在玻璃反应釜中间歇进行,在反应釜下埋入紫外线灯,并采用玻璃管作为送风装置。研究了不同波长UVA(365 nm)、UVB(311 nm)、UVC(254 nm)和真空UV光(185 nm)在浸出液中的行为。所有实验在相同条件下,在有和没有紫外线灯的情况下进行比较。研究了自由基形成机制对浸出环境的适应性及其在氧化溶液介质浸出中的可用性。在紫外光(185 nm)和非紫外光条件下,铜的提取率分别为85.1%和70.7%。综上所述,在紫外(185 nm)光反应器体系中,铜渣在最佳条件下的金属溶解率比无紫外光反应器体系效率更高。光化学反应器是使其适应湿法冶金应用和检验工艺的新途径。

Relational Turkish Text Classification Using Distant Supervised Entities and Relations

Text classification,by automatically categorizing texts,is one of the foundational elements of natural language processing applications.This study investigates how text classification performance can be improved through the integration of entity-relation information obtained from the Wikidata(Wikipedia database)database and BERTbased pre-trained Named Entity Recognition(NER)models.Focusing on a significant challenge in the field of natural language processing(NLP),the research evaluates the potential of using entity and relational information to extract deeper meaning from texts.The adopted methodology encompasses a comprehensive approach that includes text preprocessing,entity detection,and the integration of relational information.Experiments conducted on text datasets in both Turkish and English assess the performance of various classification algorithms,such as Support Vector Machine,Logistic Regression,Deep Neural Network,and Convolutional Neural Network.The results indicate that the integration of entity-relation information can significantly enhance algorithmperformance in text classification tasks and offer new perspectives for information extraction and semantic analysis in NLP applications.Contributions of this work include the utilization of distant supervised entity-relation information in Turkish text classification,the development of a Turkish relational text classification approach,and the creation of a relational database.By demonstrating potential performance improvements through the integration of distant supervised entity-relation information into Turkish text classification,this research aims to support the effectiveness of text-based artificial intelligence(AI)tools.Additionally,it makes significant contributions to the development ofmultilingual text classification systems by adding deeper meaning to text content,thereby providing a valuable addition to current NLP studies and setting an important reference point for future research.

从铜渣中获得工业醋酸铜(Ⅱ)溶液的常压浸出条件和浸出动力学研究

从铜渣中回收有价金属的技术虽然很多,但其经济和环境相容性都不理想。用双氧水和有机酸乙酸研究了铜渣中金属在常压下的溶解行为。该渣为转炉渣和闪速炉渣的混合物,含Cu 6.74%,Zn 4.34%,Fe 36.45%。常规的常压浸出实验在100 mL的玻璃烧杯中进行,在磁力搅拌器中使用涂有聚四氟乙烯的磁性搅拌棒。在最佳浸出条件下,铜提取率为98.04%,锌提取率为28.8%,铁提取率为2%。拉曼光谱显示Cu^(2+)/Zn^(2+)与AcO^(-)(乙酸)存在配位。溶解过程用一级动力学方程描述。表观活化能为23.7 kJ/mol,表明溶解过程受扩散控制。H_(2)O_(2)和CH_(3)COOH的反应级数分别为1.24和0.1。本文提出的湿法冶金新工艺简单、环保,在常规条件下从铜渣中获得醋酸铜溶液的性能明显优于其他方法。

Microstructure and mechanical properties of friction-stir welded St52 steel joints

The aim of this work is to investigate the mechanical properties and microstructures of friction-stir welded(FSWed) St52 structural steel joints. In this study, St52 steel plates with a thickness of 4 mm were butt-welded by friction-stir welding(FSW) using a tungsten carbide tool having a conical pin. The microstructure of the welded zone consists of equiaxed fine ferrite, grain boundary ferrite, Widmanstatten ferrite, and aggregates of ferrite + cementite. The microhardness measurements showed that the hardness of the welded zone was significantly higher than that of the base metal. The FSWed St52 joint exhibited a significant strength overmatching in the weld region and a strength performance similar to or slightly higher than that of the base plate.

Prediction of Leakage from an Axial Piston Pump Slipper with Circular Dimples Using Deep Neural Networks

Oil leakage between the slipper and swash plate of an axial piston pump has a significant effect on the efficiency of the pump.Therefore,it is extremely important that any leakage can be predicted.This study investigates the leakage,oil film thickness,and pocket pressure values of a slipper with circular dimples under different working conditions.The results reveal that flat slippers suffer less leakage than those with textured surfaces.Also,a deep learning-based framework is proposed for modeling the slipper behavior.This framework is a long short-term memory-based deep neural network,which has been extremely successful in predicting time series.The model is compared with four conventional machine learning methods.In addition,statistical analyses and comparisons confirm the superiority of the proposed model.

The Investigation of K Shell X-Ray Fluorescence Parameters for Sulphur Atom in Different 1,2,4-Triazoles

The measurement of K shell fluorescence parameters is an easy and practical way to investigate the electronic structures of elements in alloys,compounds or complexes.Since the number of valence electrons will change the screening effect,the measured parameters will be affected from the changes.In this study,the measured parameters were investigated for sulphur element according to the number of CH_2 groups.For the experimental measurements,the samples were excited by 59.5keVγrays from a 241 Am annular radioactive source.The emitted K X-rays from the samples were counted by ab Ultra-LEGe detector with a resolution of 150 eV at 5.9keV.

Simulated and experimental studies of a multi-band symmetric metamaterial absorber with polarization independence for radar applications

We develop a simple new design for a multi-band metamaterial absorber(MTMA)for radar applications.Computer Simulation Technology(CST)Studio Suite 2018 was used for the numerical analysis and absorption study.The simulated results show four high peaks at 5.6 GHz,7.6 GHz,10.98 GHz,and 11.29 GHz corresponding to absorption characteristics of 100%,100%,99%,and 99%,respectively.Furthermore,two different structures were designed and compared with the proposed MTMA.The proposed structure remained insensitive for any incident angle and polarization angle from 0°to60°.Moreover,negative constitutive parameters were retrieved numerically.To support the simulated results,the proposed design was fabricated by using a computer numerical control-based printed circuit board prototyping machine and tested experimentally in a microwave laboratory.The absorption mechanism of the proposed MTMA is presented through the surface current and electric field distributions.The novelties of the proposed structure are a simple and new design,ease of fabrication,low cost,durability,suitability for real-time applications and long-term stability given the fabrication technique and non-destructive measurement method and very high absorption.The proposed structure has potential applications in C and X band frequency ranges.

Tunable left-hand characteristics in multi-nested square-split-ring enabled metamaterials

Left-hand materials have drawn increasing attention from many disciplines and found widespread application, especially in microwave engineering. A sandwiched metamaterial consisting of multi-nested square-split-ring resonators on the top side and a set of wires on the back side is proposed. Scattering parameters are retrieved by high-frequency structure simulator(HFSS) software based on the finite element method. Effects of square-split-ring number on the left-hand characteristics containing negative values of permittivity, permeability, and refractive index have been intensively investigated. Simulated results show that obvious resonant left-hand characteristics could be observed within 8-18 GHz, and the resonant frequency counts are inclined to be in direct proportion to the square-split-ring number over 8-18 GHz. Besides, the proposed sandwiched metamaterial with three square-split-ring resonators and three wires presents the widest frequency band of left-hand characteristics in a range of 8-18 GHz. Further, electromagnetic field distributions demonstrated that the induced magnetic dipole dominates the resonant absorption. The multi-peak resonance characteristics of square-split-ring resonant structure are considered to be a promising candidate for selective-frequency absorption or modulation toward microwave frequency band.

Genetic Bioengineering in the Achievement of Algae Biofuels and High-Value Bio-products

The dependence to fossil fuels has increased the amount of greenhouse gases in the atmosphere.That is why,the production of renewable and sustainable biofuels has gained a long-term importance for both scientific and political necessities.In this context,algae are promising in terms of alternative biofuels resources.For this reason,intensive scientific researches have been carried out in recent years on providing optimum efficiency in this regard.Bioengineering is a discipline that applies engineering principles of design and analysis to biological systems and biomedical technologies.Examples of bioengineering research include bacteria or microalgae engineered to produce valuable bioactive chemicals.Microalgae by target gene modification may serve as a promising source for the production of biofuels and bio-based chemicals.A lot of research has been carried out by applying microalgae genomic editing technique with the aim to produce numerous biotechnological products.Some successful previously reported research and production activities are still underway in this area.However,in order to produce the desired products efficiently with manipulated microalgae biorefinery,there is a need to overcome the problem of low biomass production despite high production costs.The aim of this work is to give special attention to the rich potential content of microalgae and to provide information on algal genetic manipulations to increase products by bioengineering methods.

A Preliminary Technique for the Isolation and Culture of Brown Trout(Salmo trutta macrostigma,Dumeril,1858)Spermatogonial Stem Cell

This study was aimed to find a practical technique for isolation and culture spermatogonial stem cells from male brown trout(Salmo trutta macrostigma).Twelve wild juvenile male were obtained from K?l?cTrout Fish Farm(Kahramanmara?,Turkey).The juveniles were taken alive to the aquaria unit and stored in a 1000-liter capacity fiberglass tank.In order to identify the best size,age and testis structure of S.t.macrostigma for spermatogonial stem cell isolation and culture.Morphological and histological testis conditions were assessed.Fish were anesthetized with 0.04%2-phenoxethanol.The surface of the fish was sterilized with 70%ethanol.Twelve fish were divided into two groups for enzyme digestion,and each group was divided into two replicates(three fish per replicate).Testis tissue of group one were digested by 0.25%trypsin-EDTA,and testis tissues of group two were digested by 0.05%trypsin-EDTA.At the end of the trial,first,the best age,size and weight of the male fish for spermatogonial stem cell isolation and culture were identified as 5+month old,12.13±1.5 cm,19,25±7.05 g respectively.Then,the highest spermatogonial stem cells were measured in the stage one and two of the testes.Finally,isolation and culture conditions were optimized for male S.t.macrostigma.Spermatogonial stem cell isolation and culture techniques were defined for fish in order to be used in surrogate reproduction technologies and gene transfer systems.

Electricity Generation by Solar Energy in Turkey： Current State and Outlook

Turkey is in good condition in terms of solar energy because of the fact that, Turkey falls in between 40 degree North and 40 degree South latitude which is called as ＂sunbelt＂. The potential of producing electric from solar energy is very high in terms of potential of Turkey. According to a report by the Turkish Energy Ministry, Turkey＇s average rate of electrical energy consumption increased to levels 5.59 in the last 11 years. Moreover, solar energy may be primary energy source on account of the fact that, Turkey is in the position of a country importing energy and has signed Kyoto Protocol of carbon emission to atmosphere. The aim of the article is to give information about acts need to be done and present policies of Turkey on producing electric from solar energy. Beyond question, the policies of the government will determine the direction of developmental momentum of energy industry in Turkey as whole world will. The present support to production of electric from solar energy is not enough, so it is needed to give much higher level of support to this sector. In this context, it is essential to enhance guarantied tariff cost and the power of unlicensed electric production.

Origin of Dolomitization in Demirkazik Formation(Adana-Turkey)

Demirkaz&#305k formation consisting of the limestones and dolomites is common in the Adana, Turkey. In this study, it is aimed to find the origin of dolomitization by preparing a detailed geological map. For this purpose, firstly, thin section/polished section and, chemical analysis of the twenty-one samples characterizing dolomitization of the field were prepared and examined. In the chemical analyzes, 21 samples were determined MgO-CaO ratio. Geological map was prepared by field study and MgO contents of the samples that are known coordinates in the chemical data, and the regions where dolomitization was effective were determined. Dolomitization in these carbonates occurs at early stages and late stages. Two dolomite types are petrographically determined;(1) fine crystalline dolomite (TD-1) with 10 - 25 μm crystal size and (2) coarse crystalline dolomite (TD-2) with 50 - 120 μm crystal size. TD-1 is formed by synsedimentary replacement and TD-2 derived from TD-1. The evidence of dolomitization due to pressure changes in the TD-2 dolomites is evidence of late diagenetic. There are three types of carbonate by chemical data;limestone, dolomitic limestone, calcitic dolomite and MgCO3 ratio of these is increased respectively. The rate of dolomitization is very variable and at the fracture regions, the Mg ratio increases, indicating that tectonism is the cause of dolomitization.

Copolymerization of Azobenzene-bearing Monomer and 3,4-Ethylenedioxythiophene(EDOT): Improved Electrochemical Performance for Electrochromic Device Applications

In this study,novel electrochromic copolymers of 3,4-ethylenedioxythiophene(EDOT)and(E)-1,2-bis(2-fluoro-4-(4-hexylthiophen-2-yl)phenyl)diazene(M1)with different monomer feed ratios were designed and synthesized electrochemically.Electrochemical and spectroelectrochemical characterizations were performed using voltammetry and UV-Vis-NIR spectrophotometry techniques to test the applicability of copolymers for electrochromic applications.In terms of electrochemical behaviors,addition of an electron-rich EDOT unit into the azobenzenecontaining copolymer increased the electron density on the polymer chain and afforded copolymers with very low oxidation potentials at around0.30 V.While the homopolymers(P1 and PEDOT)exhibited neutral state absorptions centered at 510 and 583 nm,EDOT-bearing copolymers showed red shifted absorptions compared to those of P1 with narrower optical band gaps.In addition,the poor optical contrast and switching times of azobenzene-bearing homopolymer were significantly improved with EDOT addition into the copolymer chain.As a result of the promising electrochromic and kinetic preperties,Co P1.5-bearing single layer electrochromic device that works between purple and light greenish blue colors was constructed and characterized.