Defects

Aluminium is invariably present in both synthetic
and natural quartz crystals which exists as a
substitution for silicon. The trivalent aluminium can
make only three of the bonds normally made by a silicon
and hence a negative charge exists on the site
due to the fourth non-bonding oxygen. This charge is
compensated by impurity ions which are bound electrostatically
in an adjacent *-axis channel. During
sweeping the compensating impurity ions which are
weakly bound near the aluminium atoms move toward the
cathode. This result in the collection of negative
space charges near the anode side of the crystal
deforming the lattice. X-ray transmission topographs
recorded from vacuum swept quartz crystals show a
strong dark contrast near the anode side of the
crystals due to lattice strain. This strong X-ray
topographic contrast disappears when the crystals
are subjected to prolonged X-ray irradiation. The
negative charge formed near the anode side of the
crystals during sweeping is compensated by forming
aluminium-hole and aluminium-hydroxyl centres during
the irradiation

Investment casting process is used worldwide to manufacture as cast precision castings specially for super alloy castings mainly for Aerospace and Automotive Industry. The process of investment castings is very complicated compared to other commonly used casting processes. Very crucial stages in this process are 1) first coat of zircon silica on pattern assembly and 2) Metal pouring in preheated shells. These two stages of the investment casting processes are usually performed manually in small scale Investment casting foundries causing defects which increase the cost of quality and scrap. This increases delivery lead time affecting profit gains. This scenario is typical for small scale investment casting foundries making small yet high production castings.

Requirements defects have a major impact throughout the whole software lifecycle. Having a specific defects classification for requirements is important to analyse the root causes of problems, build checklists that support requirements reviews and to reduce risks associated with requirements problems. In our research we analyse several defects classifiers; select the ones applicable to requirements specifications, following rules to build defects taxonomies; and assess the classification validity in an experiment of requirements defects classification performed by graduate and undergraduate students. Not all subjects used the same type of defect to classify the same defect, which suggests that defects classification is not consensual. Considering our results we give recommendations to industry and other researchers on the design of classification schemes and treatment of classification results.

the pattern of partial discharge (PD) occurrence at a defect site within a solid dielectric material is influenced by the conditions of the defect site. This is because the defect conditions, mainly its size and location determine the electric field distributions at the defect site which influence the patterns of PD occurrence. A model for a spherical cavity within a homogeneous dielectric material has been developed by using Finite Element Analysis (FEA) software. the model is used to study the influence of different conditions of the cavity on the electric field distribution in the cavity and the PD activity. in addition, experimental measurements of PD in spherical cavities of different size within a dielectric material have been undertaken. the obtained results show that PD activity depends on the size of the cavity within the dielectric material. © 2009 IEEE.

http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=5252384

Cracks are typical line structures that are of interest in many computer-vision applications. In practice, many cracks, e.g., pavement cracks, show poor continuity and low contrast, which brings great challenges to image-based crack detection by using low-level features. In this paper, we propose DeepCrack-an end-to-end trainable deep convolutional neural network for automatic crack detection by learning high-level features for crack representation. In this method, multi-scale deep con-volutional features learned at hierarchical convolutional stages are fused together to capture the line structures. More detailed representations are made in larger-scale feature maps and more holistic representations are made in smaller-scale feature maps. We build DeepCrack net on the encoder-decoder architecture of SegNet, and pairwisely fuse the convolutional features generated in the encoder network and in the decoder network at the same scale. We train DeepCrack net on one crack dataset and evaluate it on three others. The experimental results demonstrate that DeepCrack achieves F-Measure over 0.87 on the three challenging datasets in average and outperforms the current state-of-the-art methods.

Requirements defects have a major impact throughout the whole software lifecycle. Having a specific defects classification for requirements is important to analyse the root causes of problems, build checklists that support requirements reviews and to reduce risks associated with requirements problems. In our research we analyse several defects classifiers; select the ones applicable to requirements specifications, following rules to build defects taxonomies; and assess the classification validity in an experiment of requirements defects classification performed by graduate and undergraduate students. Not all subjects used the same type of defect to classify the same defect, which suggests that defects classification is not consensual. Considering our results we give recommendations to industry and other researchers on the design of classification schemes and treatment of classification results.

En este trabajo se revisa la metodología utilizada por los autores para estudiar causas de defectos en productos de aceros al carbono en plantas de América Latina, y los diferentes reactivos metalográficos que pueden ser utilizados para brindar mayor información acerca del origen de los mismos. Se centra en defectos observados en productos largos de aceros al carbono, tales como alambrón de acero de bajo, medio y alto carbono, barras para construcción mecánica de bajo y medio carbono, barras para refuerzo de hormigón, planchuelas y perfiles.

O trabalho revisa o tema dos defeitos superficiais em tarugos de diversas qualidades de aços ao carbono e de baixa liga obtidos por lingotamento com jato aberto ou válvula submersa e lubrificação com azeite ou pó fluxante. Utiliza-se a observação visual e mediante microscópio stereo do defeito; o estudo metalográfico; o estudo das variáveis de processo e equipamento que influem na geração dos defeitos; a análise da bibliografia sobre o problema, a evolução do defeito durante a laminação e a influência no produto laminado. Entre os defeitos superficiais comuns na produção de tarugos, discute-se a porosidade superficial, as trincas transversais, as depressões e trincas longitudinais, a dupla pele, a escória etc. Recentemente, também se presta atenção à interação entre qualidade superficial, interna e de forma, visando obter uma casca ou camada chill de espessura importante e uniforme. A identificação precisa das características dos defeitos facilita a compreensão das causas que os originam, permite a aplicação de medidas corretivas certas, e senta as bases para evitar no futuro a recorrência do problema sob novas condições.

The work reviews the issue of surface defects in billets of different carbon and low alloy steel grades, cast with metering nozzle or submerged entry nozzle, and with oil or casting powder lubrication. Naked eye and stereo microscope observation; metallographic study; review of process and equipment variables with influence on the generation of defects, literature review, evolution of defects during rolling and influence on the final product are taken into account. The discussion includes most common defects in billets, like pinholes, transverse cracks, longitudinal cracks and depressions, double skin, slag entrapment, etc. Recently, attention is paid to interaction between surface, inner and shape quality, and evenness / thickness of the shell layer. The precise identification of the defect features makes easier the understanding of the root cause of their origin, helping in the application of corrective measures and giving place to sound bases to avoid the comeback of the problem under new conditions.

The readymade garment industry is the leading industry in Bangladesh that's why the Quality improvement of garments can play a vital role. The main purpose of this paper is to reduce the defects that will minimize the rework rate. We worked at " Interstoff Apparels Limited " , Bangladesh identifying sewing defects for a particular product (knit T-Shirts). Pareto analysis is performed to identify top defect positions from all the defects and seven are identified where 80% defects occur which should be the major concerning areas to minimize defects percentage. Cause-effect diagrams are constructed to show the root cause, effect, and 5S & PDCA is used to minimize the defects effectively. Recommendations have been added at the end of the study.

Abstrak Dalam dunia industri kualitas produk adalah salah satu faktor yang paling penting untuk produk yang dihasilkan. Contoh nya pada PT.XYZ yang merupakan perusahaan manufaktur yang memproduksi sepatu. Sepatu merupakan salah satu kebutuhan primer yang harus di penuhi manusia. Karena manusia beraktivitas pasti menggunakan sepatu untuk melindungi kaki dari kegiatan aktivitas yang dilakukan. Manfaat dari sepatu tidak hanya untuk melindungi kaki tetapi bisa membuat seseorang lebih percaya diri karena sepatu yang digunakan berkualitas tinggi dan desain sepatu yang dapat mempercantik penampilan. Salah satu model sepatu yang di produksi oleh PT.XYZ ialah Classic Cortez. Model sepatu tersebut di buat dari material kulit hewan yaitu sapi. Material kulit tersebut akan di buat menjadi komponen sepatu yang disebut quarter. Akan tetapi, banyak timbul permasalahan yang terjadi oleh komponen quarter tersebut, seperti terjadinya cacat pada komponen quarter. Maka, tujuan penelitian ini dilakukan untuk mengidentifikasi penyebab khusus cacat pada komponen quarter yang melewati upper control limit (UCL) dan lower control limit (LCL), mengidentifikasi proporsi cacat yang banyak terjadi, mengidentifikasi penyebab utama masalah pada komponen quarter dan mengidentifikasi apa yang menjadi risiko kegagalan dalam proses pembuatan sepatu model Classic Cortez. Penelitian tersebut dilakukan dengan menggunakan metode peta kendali atribut Np, diagram pareto, diagram fishbone dan failure mode and effect analysis (FMEA). Hasil yang diperoleh pada peta kendali Np terdapat cacat pada komponen quarter yang melewati upper control limit (UCL) dan lower control limit (LCL) yang disebabkan karena faktor 5M+1E. Kemudian pada diagram pareto didapatkan jenis cacat tertinggi ialah Cacat Kulit dengan jumlah 116 unit dan persentase kecacatan sebesar 42%. Kemudian penyebab utama Cacat Kulit dibuat fishbone diagram 4M dimana setelah di analisa akar permasalahan terjadi pada bone material. Serta potential failure mode yang terpilih dari lima jenis cacat ialah Cacat Kulit, Keriput dan Robek serta rekomendasi aksi yang diberikan kepada PT.XYZ ialah audit vendor dan schedule maintenance. Kata Kunci : peta atribut np, diagram pareto, diagram fishbone, failure mode and effect analysis Abstract In the industrial world product quality is one of the most important factors for the product produced. For example, PT. XYZ, which is a manufacturing company that manufactures shoes. Shoes are one of the primary needs that must be fulfilled by humans. Because human activities must use shoes to protect the feet from the activities carried out. The benefits of shoes are not only to protect the feet but can make a person more confident because the shoes used are high quality and shoe designs that can enhance your appearance. One model of shoes produced by PT. XYZ is Classic Cortez. The shoe model is made from animal skin material, cow. The leather material will be made into a shoe component called the quarter. However, many problems arise by the quarter component, such as the defects in the quarter component. Thus, the purpose of this study is to identify the specific causes of defects in the quarter component that pass through the upper control limit (UCL) and lower control limit (LCL), identify the proportion of defects that occur, identify the main causes of problems in the quarter component and identify what are the risks failure in the

Abstrak— Stainless steel A/SA-312 TP304 merupakan stainless steel seri austenitic yang mengandung 16-20% kromium, 7-22% nikel, dan nitrogen dimana memiliki karakteristik sifat ketahanan korosi yang tinggi dan juga ketangguhan yang baik pada temperatur cryogenic. Material stainless steel seri ini sering dijumpai pada jaringan perpipaan pada kapal LNG carrier dimana pada tahap fabrikasi dan konstruksinya tidak luput dari proses pengelasan. Namun kasus yang ditemui dilapangan adalah menurunnya sifat ketahanan korosi dikarenakan terjadinya chromium depletion paska pengelasan. Oleh karena itu pada setiap pengelasan austenitic stainless steel selalu ditambahkan perlakuan back purging saat proses pengelasan dengan tujuan untuk melindungi daerah root pada pipa dari oksidasi yang dapat menyebabkan terjadinya korosi. Pada penelitian ini dilakukan 2 variabel gas back purging antara gas argon (Ar) dan nitrogen (N) pada pengelasan GTAW austenitic stainless steel A/SA-312 TP304 kemudian dilakukan pengujian hardness, impact, corrosion rate serta analisa terhadap defect atau discontinuity yang mungkin akan terjadi. Hasil dari penelitian ini menunjukkan bahwa variasi gas back purging antara gas argon dan gas nitrogen tidak terlalu signifikan terhadap hardness value, impact value serta discontinuity yang terjadi, tetapi perbedaan variasi gas back purging sangat mempengaruhi corrosion resistant pada hasil logam lasan dimana pemilihan gas back purging terbaik terdapat pada pemilihan gas argon dengan nilai laju korosi sebesar 0.040988 mmpy sedangkan pada pemilihan gas nitrogen sebesar 0.133200 mmpy.

Condition monitoring has become a cornerstone of predictive/condition based maintenance. With knowledge of the operating condition of a machinery ( in this case the gas turbine), Operators and maintenance personnel alike can be warned in advance of an impending fault and potential failure Thus enabling maintenance planning in an optimized manner with the ultimate goal of reducing maintenance cost since a significant portion of all operating cost results from maintenance. The purpose of this paper is to examine the basic practices in condition monitoring of gas turbine. It looks at the various condition monitoring techniques with more details on vibration analysis since it is the most useful and arguable the best condition monitoring technique. It also examined the two major condition monitoring systems (i.e. online and offline systems), the merit and challenges of this maintenance management tool. The importance and benefits of condition monitoring was established. However major challenge now inherent in modern condition monitoring practices is the extent or scope of condition monitoring to embark on. This can only be ascertained only when a proper detailed evaluation of the profitability of the proposed system is carried out.

This research study proposes an innovative analysis for controlling the defects in aluminium die casting industry. In this analysis, casting process of a two-stroke engine oil pump body is concentrated. The component selected has often rejected due to blow hole defects. Six Sigma, the zero defect approach, is used in this study. Define measure, analyse, improve and control (DMAIC) problem solving methodology is applied for problem analysis. Taguchi's experimental design is used for process validation and improvement. The confirmation experiment showed that the rejection rate was reduced to 4.8% from 17.22%. The application of Six Sigma program with Taguchi technique has developed an innovative cost effective methodology for controlling defects in die casting process in less experimental time.

Injection moulding is one process to form plastic by compress the melted plastic in a closed die. The raw material for the process either pure plastic pellet or mixed with recycled plastics. this research focused on finding the acceptable percentage of recycled the raw material in term of tensile strengh and shrinkage. The composition is varied from 0% to 100% of polyethylene. Tensile test shows that the more percentage of recycled the lower is the tensile strenght. on the other hand, the more the recycled composition the highernis shrinkage number. Both decrease of tensile strengh and increase of shrinkage are linearly. Recycled plastic in the raw material makes the composition be not uniform. It leads misrun defect, i.e. the melted plastic solidified before it reach the destined cavity in the mold. Moreover, it also creates more void in the parts. The highest tensile strength of 19.10 N/mm 2 when no recycled mixed in, whereas the minimum of 12.05 N/mm 2 achieved when 100% recycled was applied. Recycled Composition of 100% also increased by 9,82% compare to pure plastic.

Atom-thick two-dimensional materials usually possess unique properties compared to their bulk counterparts. Their properties are significantly affected by defects, which could be uncontrollably introduced by irradiation. The effects of electromagnetic irradiation and particle irradiation on 2H MoS2 two-dimensional nanolayers are reviewed in this paper, covering heavy ions, protons, electrons, gamma rays, X-rays, ultraviolet light, terahertz, and infrared irradiation. Various defects in MoS2 layers were created by the defect engineering. Here we focus on their influence on the structural, electronic, catalytic, and magnetic performance of the 2D materials. Additionally, irradiation-induced doping is discussed and involved.

This work is focused on the defects observed in low, medium and high
carbon wire rod, bar, rebar, flats and shapes, originated in continuous casting or rolling. The study of defects has many aspects to be taken into account before metallographical analysis. The general information about the defect like frequency, size, shape and position, based on naked eye observation, is very important. It is also a must the observation with stereo microscope of the surface, as rolled or descaled with mechanical or chemical methods (sand blasting, shot peening or pickling). The study
of the internal quality of continuous casting products based on transverse cuts can also give relevant information to find out the origin of the defects. The metallographical study of polished samples includes their observation in the light microscope, in the as-polished state or after etching with different reagents. Depending of the steel grade and the problem being searched, nital, Oberhoffer´s, alkaline sodic chromate, Béchet Beaujard´s or other etchants can be selected. Each one gives different insights on the process step where the defect started, its possible location in the parent as-cast product, its evolution during preheating or rolling, etc. Extra information can be taken from the SEM and EDS analysis (especially when the defect is associated with non-metallic inclusions or fracture). Follow-up of continuous casting and rolling process and in-plant tests are useful tools in order to verify hypotheses and to improve practices to avoid defects. Literature
surveys usually give insight, as defects are usually repetitive from plant to plant.

In order to minimise surface defects in long products, their origin needs to be assessed. To this purpose, a methodology was developed, that includes metallographic studies on bar and wire rod using several reagents. A description is made of the different steps involved in this method, including the use of etchants to determine the former position of the defect in the billet, oxygen penetration, etc. It is also discussed the interpretation given to internal oxidation, scale inside the defect, decarburisation, partial welding and other metallographic features. A discussion of pin holes and transverse cracks on billets is made, taking into account its aspect and metallographic features on the billet, the evolution during reheating and rolling and the final aspect and metallographic features on the bar/wire rod. Root causes for formation of these defects and solutions recommended are analysed for each case. The paper is based on experience made by IAS Technical Centre while troubleshoo...

Gojjam zone at three woredas (Dejen, Sinan and Awable). Three warehouses from each woreda were purposively selected and used to generate the data from cow hide, sheep and goat skins. 10% of the total stocks were taken randomly from each warehouse and a total of 180 hides, 2250 sheep skin and 765 goat skins were examined by using close observation. Hides and skins were graded according to the standard set by the Ethiopian Quality and Standard Authority. From these amounts, 74 (41.1%) hides, 750 (33.3%) sheep skins, 151 (31.4%) wet salted and 88 (30.9%) air dried goat skins were grade I; 90 (50%) hides, 1380 (61.3%) sheep, 261 (54.4%) wet salted and 168 (58.9%) air dried goat skins were grade II; 16 (8.9%) hides, 120 (5.3%) sheep skins, 67 (14%) wet salted and 29 (10.2%) air dried goat skin were grade III; and 1 (0.2%) wet salted goat skin was grade IV. The leading observed defects that downgrade the hides were filthiness with a value of 142 (17.9%), gouge mark with a value of 140 (17.7%) and poor pattern with a value of 107 (13.5%). Poor pattern and salt pitting on the hide showed a significant difference at P<0.05 significant level. However there is no significant difference on other defects. The observed primary defects on the sheep skin were filthiness with a value of 494 (22%), poor pattern with a value of 319 (14.2%) and gouge mark with a value of 221 (9.8%). Fly cut, poor pattern, salt crystallization and hard spot showed a marked statistical difference at p<0.05 significant level. The most important defects observed on the wet salted goat skin were filthiness with a value of 136 (28.3%), poor pattern with a value of 88 (18.3%) and fly cut with a value of 75 (15.6%). In this case, poor pattern, filthiness, scores, salt crystallization and salt pitting have shown a significant difference between woredas at P<0.05 significant level. Filthiness with a value of 88 (28.8%), poor pattern with a value of 40 (14%) and fly cut with a value of 32 (11.2%) were the forefront defects of air dried goat skin. Fly cut, poor pattern, corduroying, filthiness and weak spot have shown a statistical significant difference at P<0.05 significant level. This indicates that most defects on hides and skins occurred during slaughtering operations. Therefore, more attention should be taken during slaughtering of animals to get quality hides and skins for national as well as international market, and maximize the country's foreign currency exchange.

Defect in a cable joint is one of the main reasons of a power system being faulty. A defect can cause the electric field in the cable joint to become higher than the material surrounding the defect. This may result in partial discharge (PD) activity to occur within the defect site. When PD is repeating at the defect site, the material surrounding the defect will be affected, where PD may extend its path in the material. This may result in a breakdown at cable joint and consequently causes breakdown on the whole system. Therefore, the purpose of this research is to study the electric field distribution in 132 kV one piece premolded cable joint with and without the presence of defects. A better understanding of the electric field distribution at a cable joint can be attained by modelling the cable joint structure using finite element analysis (FEA) method. Through modelling and simulation results obtained in this work, an understanding of the electric field distribution in defects within cable joint structure can be enhanced. © 2012 IEEE.

http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=6416227

This work reports an electron beam irradiation (30 kGy and 90 kGy) approach to narrow the band gap of the pristine CeO2 nanostructure (p-CeO2) to enhance their visible light activity through defect engineering. This was confirmed by diffuse reflectance spectroscopy, photoluminescence, Raman spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller, electrochemical impedance spectroscopy, and linear scan voltammetry. XPS revealed changes in the surface states, composition, Ce4+ to Ce3+ ratio, and other defects in the modified CeO2 nanostructures (m-CeO2). The m-CeO2 exhibits excellent photocatalytic activities by degrading 4-nitrophenol and methylene blue in the presence of visible light (λ > 400 nm) compared to the p-CeO2. The optical, photocatalytic, and photoelectrochemical studies and proposed mechanism further support the enhanced visible light photocatalytic activities of the m-CeO2. This study confirmed that defect-induced band gap engineered m-CeO2 could be used effectively as photocatalyst and photoelectrodes owing to their enhanced visible light photocatalytic activities.

In order to minimise surface defects in long products, their origin needs to be assessed. To this p urpose, a methodology was developed, that includes metallographic studies on bar and wire rod using several reagents. A description is made of the different steps involved in this method, including the use of etchants to determine the former position of the defect in the billet, oxygen penetration, etc. It is also discussed the interpretation given to internal oxidation, scale inside the defect, decarburisation, partial welding and other metallographic features. A discussion of pin holes and transverse cracks on billets is made, taking into account its aspect and metallographic features on the billet, the evolution during reheating and rolling and the final aspect and metallographic features on the bar/wire rod. Root causes for formation of these defects and solutions recommended are analysed for each case. The paper is based on experience made by the authors while troubleshooting defect problems in carbon steel long products at South American steel plants.

Laser welding is a rapidly evolving and flexible technology that has found increasing industrial and manufacturing applications. It enables the precise welding of small and hard-to-reach areas and is particularly suitable for computer or robotic control operations. The laser welding technology describes the latest developments in the field and how they can be used across a wide range of applications. The fundamentals of laser welding discuss advancement in proven technologies such as CO2 disk laser welding, laser welding, and laser micro welding technology. Laser welding is a technique for aluminium and titanium alloys, plastics and glass. Applications of laser welding robotics and advances in laser and hybrid laser welding modelling and simulation. Laser welding applications is used in the automotive, rail and shipbuilding sectors. Due to its high precision, high-energy concentration and rapid processing potential, laser welding is particularly suitable for joining copper alloys in this context. High laser power needed due to low laser absorption, high copper thermal conductivity and low process stability. Laser welding of copper to other metals particularly copper to aluminium and copper to steel dissimilar alloys in terms of structure and properties relationships were also discussed.

In this article, the gas sensing properties of Al-doped ZnO thin films have been reported where the nanocrystalline ZnO based thin films were well deposited by a simple and inexpensive 'chemical spray pyrolysis (CSP)' technique. Films have been found to be uniform, pinhole free and well adherent to the substrate. The morphology, structures, and surface roughness of the deposited Al-doped ZnO thin films were studied by various types of characterization techniques. In addition, the authors have observed that the sensor response and selectivity towards CO gas is improved by the Al doping at a low operating temperature. XRD results showed that the obtained films are nanocrystalline in nature with hexagonal wurtzite phase. Further, the annealed films were used for detection of CO in the air and maximum response was observed at 175 °C. The improvement in sensor response of Al-doped ZnO thin films to CO gas attributed to the defect chemistry, crystallite size and surface roughness.

Requirements defects have a major impact throughout the whole software lifecycle. Having a specific defects classification for requirements is important to analyse the root causes of problems, build checklists that support requirements reviews and to reduce risks associated with requirements problems. In our research we analyse several defects classifiers; select the ones applicable to requirements specifications, following rules to build defects taxonomies; and assess the classification validity in an experiment of ...

Hexagonal binary intermetallics A 5 B 3 has a unique A 6 octahedra chain structure , providing space for interstitial chemical engineering the physical, mechanical, electrical, and chemical properties without change in the basic structure of crystal. Because of the engineering importance of Zr-Sn alloy, here, we investigate the influence of 24 interstitial alloying elements X (X = B, and Sn) on stability and properties of hexagonal Zr 5 Sn 3 via first-principles calculations. A general trend is that the additional element with small atom size and high electronegativity is favorable as interstitials in Zr 5 Sn 3. The calculated formation enthalpy and the elastic constants suggest that these Zr 5 Sn 3 X structures are thermodynamically and mechanically stable. The calculated phonon spectra indicate that Zr 5 Sn 3 X structures are dynamically stable except X = V, Cr, Mn, Zn, and Nb. We show that their electronic structures including bonding characters have strong correlation with the stability and mechanical properties. With strong covalent bonds, Zr 5 Sn 3 B has the highest Young's modulus, bulk modulus, shear modulus, Debye temperature, and microhard-ness. The addition of alloying elements decreases the anisotropy except X = O, Sc, Ti, V and Nb. All the additive elements increase the specific heat capacity of Zr 5 Sn 3. Our results could be helpful in designing and improve the performance of Zr-Sn alloy on demand.

In software debugging, fault localization is the most difficult, expensive, tedious, and timeconsuming task, particularly for large-scale software systems. This is due to the fact that it requires significant human participation and it is difficult to automate its sub-tasks. Therefore, there is a high demand for automatic fault localization techniques that can help software engineers effectively find the locations of faults with minimal human intervention. This has led to the proposal of implementing different types of such techniques. However, Spectrum Based Fault Localization (SBFL) is considered amongst the most prominent techniques in this respect due to its efficiency and effectiveness. In SBFL, the probability of each program element (e.g., statement, block, or function) being faulty is calculated based on the results of executing test cases and their corresponding code coverage information. However, SBFL techniques are not yet widely adopted in the industry. The rationale behind this is that they pose a number of issues and their performance is affected by several influential factors. For example, the characteristics of bugs, target programs, test suites, and supporting tools make their effectiveness differ dramatically from one case to another. There are massive studies on SBFL that cover its usage, formulas, performance, etc. So far, no dedicated survey points out comprehensively the issues of SBFL. In this paper, various SBFL challenges and issues have been identified, categorized, and discussed alongside many directions. Also, the paper raises awareness of the works being achieved to address the identified issues and suggests some potential solutions too.

Buildings of modern movement have become a subject of preservation both in the world and in Turkey as a part of recent history. Detection and diagnosis of the defects and failures occurring at these buildings is an important step to protect them that allows determining necessary measures. Building facades that are a part of building envelope are affected from exterior environmental factors such as wind, temperature changes or rain, and defects and failures may occur due to physical and chemical changes resulting from being exposed to location specific exterior conditions. The defects and failures observed may also vary depending on the technology used. Therefore, a master study is being done on defect detection and diagnosis at the facades of Turkish modern movement buildings to prepare an inspection model. In this paper, as a part of aforementioned study, preliminary outcomes based mainly on literature review will be presented and discussed. In this respect, facade characteristics and technology of Turkish modern movement buildings will be presented initially considering some buildings with potential for conservation. Defects that may occur in these technologies together with a brief explanation of the climatic conditions in Turkey, and available inspection methods to detect these defects will then be presented. Finally, the preliminary inspection model and defect detection template generated will be presented and their potentials will be discussed.

In order to minimise surface defects in long products, their origin needs to be assessed. To this purpose, a methodology was developed, that includes metallographic studies on bar and wire rod using several reagents. A description is made of the different steps involved in this method, including the use of etchants to determine the former position of the defect in the billet, oxygen penetration, etc. It is also discussed the interpretation given to internal oxidation, scale inside the defect, decarburisation, partial welding and other metallographic features. A discussion of pin holes and transverse cracks on billets is made, taking into account its aspect and metallographic features on the billet, the evolution during reheating and rolling and the final aspect and metallographic features on the bar/wire rod. Root causes for formation of these defects and solutions recommended are analysed for each case. The paper is based on experience made by the authors while troubleshooting defect problems in carbon steel long products at South American steel plants.

Hydroxyapatite (HAp), a primary constituent of human bone, is usually nonstoichiometric with varying Ca/P molar ratios, with the well-known fact that Ca deficiency can cause marked reductions in its mechanical properties. To gain insights into the mechanism of this degradation, we employ first-principles calculations based on density functional theory and determine the effects of Ca deficiency on structure, vibrational, and elastic properties of HAp. Our simulation results confirm a considerable reduction in the elastic constants of HAp due to Ca deficiency, which was experimentally reported earlier. Stress-induced transformation of the Ca-deficient defected structure into a metastable state upon the application of stress could be a reason for this. Local structural stability of HAp and Ca-deficient HAp structures is assessed with full phonon dispersion studies. Further, specific signatures in the computed vibrational spectra for Ca deficiency in HAp can be utilized in experimental characterization of different types of defected HAp.

Software Engineering which has a nitty gritty life cycle process that incorporates "Practicality investigation", "Test Plan", "Test Design", "Test Execute" and "Imperfection announcing and following". The primary plan of programming testing is to recognize all business basic deformities however much as could be expected utilizing different testing strategies. Early detection of defects in software product reduces “rework costs” as it saves time and effort in the overall testing life cycle. Say for example: We have the following software development phases namely: Requirements, Design, Coding, Testing and Deployment. Bugs/Defects can introduce in any of the said phases. Identifying the right defect at the right stage is a critical task for the testing team. This paper analyzes the application dependency structure algorithms to effectively plan the module sequences prioritize the optimized test cases using OATS (Orthogonal Array Test Strategy) technique by improving projects performance and efficiency.

Transverse cracks have been the subject of a number of studies, from industry continuous improvement reports to applied research. This paper reviews those studies, aiming to define the influence of steel type and casting conditions on the occurrence of these cracks in billets, as well as the measures taken to minimize them. Besides, a discussion of the evolution of transverse crack during rolling is carried out

Testing is the one of the important component of any software engineering process. As we talking about the software’s applications then web application is the fastest growing application now a day. So web application or web sites will be tested accurately and correctly. Web testing includes testing of various applications like configuration control, navigation control, state, database etc. Web site testing ensures that there will be no broken links, no images will be missed, there should be no spelling mistakes, no any errors or bugs in software, and the download time should not be so delay as specified. Timeliness, structural quality, content, accuracy and consistency, response time and latency and performance are the major web site‘s quality factors. Functional, browser, performance, security, usability, database etc testing are performed on any website to make it defect free. Also for any project we also need to maintain the database. So database plays very important role for every organization, so for better results testing of database is required. It is now not only the necessity of project or web application itself but of the organization also to avoid any future problems that can be come in application. As a minute fault in data base can causes data loss that may be uncover able in future. Many tools and frameworks are available for testing of databases or generate test cases to check the applications. When we test the website or any web application and there is difference between expected results and the actual results, there is defect. Defects can be classified in to 3 categories: Wrong, Missing and Extra. Errors can be classified according to priority or severity. According to the severity and priority of the defects, these can be fixed before deliver product to the client. In this paper we represent that on which we can apply tests in on database. how we can perform testing on database. We have also computed the coverage of design of test cases to maintain the quality of testing. By this, we can decrease the time, memory and cost of project to some extent, there by easing the tester to manage their testing phases easily.

Chalcogenide phase change materials are one of the major contenders for the new non-volatile memory applications. Here is reported that the switching speed of Ge2Sb2Te5 is strongly dependent on the percent of defects in the material. Using cellular automata simulations it was shown that the size of the percolation cluster is minimum, thus the switching speed is maximum, for a percent of around 25% defects in the material. This is a property of the Ge2Sb2Te5 that can be useful for new phase change materials and devices design with better switching properties.

PT. X is one of the largest toy manufacturers in the world. For PT. X, the process of shipment to distribution center often leads to defect products during the trip and the defect products often end up in the distribution center's warehouse and not being handled. Both the distribution center and PT. X consider this as a loss of $361,290 but there is still no follow-up on this issue. In order to help the company to find out the options for this issue and define what factors which significantly affect the number of defect, this research is conducted. By using fishbone diagram and analysis of variance, the factors can be defined that temperature and average speed of truck become the significant factors towards the number of defect occurred, while the length of shipping time does not really affect. The proposed options of defects that occurred are stated and calculated. It is found that the best solution of this issue is to reship and rework the defect products occurred and it costs $73,615. It is way cheaper if it is compared with the reproduction cost, which is $367,990.

O artigo aborda a relação entre as condições de fabricação por soldagem a arco elétrico, os ensaios não destrutivos convencionais (END) e o processo de qualificação / certificação / padronização das condições de fabricação e inspeção industrial (normalização).

Adicionalmente, avalia os critérios para seleção dos END e apresenta e discute os conceitos fundamentais das área da soldagem (como a diferença entre defeito e descontinuidade, solda e soldagem, ...), inspeção industrial e tecnologias correlatas.

Fonte: Revista Abendi, Edição 77, pp. 13-22, Ano IX, Fevereiro de 2017.

Heritage structures perform vital role in nation’s history, culture and signify the richness of it. To augment life and enhance strength, their restoration is very important for the future generations to have knowledge about how mankind lived in past ages. Restoration involves investigating, diagnosing and correcting deficiencies and deterioration of any structure. Identification of common defects and problems faced in old structures and devising a systematic approach towards handling these issues is civil engineer’s obligation. A case study throws light on the various problems encountered and the methods employed to tackle them. This paper focuses on such problems and methodology to handle these problems while respecting structure’s cultural integrity with the help of a case study. It also seeks to highlight the need for a greater awareness and the need to take precautionary measures of the immediate effects, and of the long-term management issues of heritage structures