Overlay Process Research Articles

Robust model-based control of multistage manufacturing processes

This paper presents a novel method that utilizes in-process measurements of product quality and models that relate those measurements with the underlying manufacturing process parameters to drive down the product quality errors via strategic adjustments of the controllable process parameters. Uniqueness of the new method is its robustness to inevitable inaccuracies in the underlying models, as well as the absence of traditional, but restrictive assumptions of Gaussianity and independence of measurement and process noise terms. The new approach was demonstrated using models and data from an automotive cylinder head machining process and an industrial-scale semiconductor lithography overlay process.

Application of Analytic Hierarchy Process in Water Resources Planning: A GIS Based Approach in the Identification of Suitable Site for Water Storage

One of the important objectives of water resources planning is to tap the maximum possible water available in the river basin that can be utilized particularly during the period of drought. This can be materialized by creating water storage structures. For this purpose initially, the first task could be the identification of suitable site for creating water storage sites. With the advent of Remote Sensing (RS) and Geographic Information System (GIS) techniques, it becomes easier for water resources planner to identify the suitable location of water storage structure within the basin. Present study demonstrates the identification of suitable location in the upper basin of Sheonath river in Chhattisgarh State, India. Based on the various physical characteristics of the basin, GIS based multi-criteria evaluation technique is being applied to determine the most suitable water storage sites. The suitable sites are assessed by considering the spatially varying parameters. These parameters include potential runoff, hydrologic soil group, land use, lineament, slope, stream order and settlement and basin area. Potential runoff is calculated from Soil Conservation Service Curve Number (SCS-CN) equation. Since, there is more than one parameter; it is significant to determine the importance of one layer over another layer. Analytic Hierarchy Process (AHP) is one of the multi-criteria decision making method resulting in the percentage relative importance. The AHP model consists of three levels objective i.e. suitable site for water storage, the parameter used and the alternatives. In the overlay process of GIS the relative importance determined by AHP is applied to produce suitable locations. Suitability is divided into three categories “suitability level 1”, “suitability level 2” and “suitability level 3” representing storage tank, stop dam and check dam respectively. This mapping helps in selecting potential site for water storage structures in the basin.

Weather Extremes, Disasters, and Collective Violence: Conditions, Mechanisms, and Disaster-Related Policies in Recent Research

Summary of research on the consequences of extreme weather events, which manifest themselves as disasters, for collective violence as well as on policy measures to mitigate such negative effects. A growing, but contested, majority of studies indicate a slight increase in the likelihood of the occurrence, escalation, and prolongation of collective violence in the wake of disasters. The identification of conditions and mechanisms, some of which increase the likelihood of violence and some of which have the opposite effect, helps us to understand the diversity of outcomes. This includes the consequences of political and humanitarian interventions prior to, during and after disasters, which can overlay local processes. Conditions and mechanisms shaping the link between disasters and collective violence provide opportunities for policy interventions that are already, or can be, taken to mitigate the consequences of extreme events, increasing or reducing the likelihood and level of collective violence.

Landslide assessment and susceptibility zonation in Ebantu district of Oromia region, western Ethiopia

The present paper deals with landslide hazards in the Ebantu district of the Oromia regional state of western Ethiopia. Ninety-two landslides were recorded during field investigations and Google Earth interpretation. The data sets were prepared as a layer in the spatial GIS database that was later utilized for generating the landslide susceptibility zonation map. Slope, elevation, and distance from drainage were extracted from the digital elevation model, the geology is modified from the geological map of Nekemte, and the land use map was prepared from Landsat +ETM satellite (2015) using digital image processing techniques. The statistical index method was applied to identify landslide hazard areas, and statistical analysis was carried out based on the relationship between past landslides and the causative factors. The causative factor map is further classified into a number of classes based on their relative influence on mass movement and rating values are assigned to each class depending on their influence on slope instability. Based on their assigned weight values, the map overlay process is performed using Arc GIS 10.3, and finally, the landslide hazard map showing various zones is produced by the overlay technique.

Site selection for avocado cultivation using GIS and multi-criteria decision analyses: Case study of Antalya, Turkey

Site selection for agricultural products is an important research area because determining accurate areas is essential for the successful growth of the products and for sustainable agriculture. The purpose of this study is to select suitable sites for avocado cultivation using geographical information system (GIS)-based multi-criteria decision Analysis (MCDA). Seven important factors for the growth of avocado trees were determined: forest border, slope, permeability, soil depth, land use capability, protected areas/forbidden zones, and average and minimum temperature. In the study, the overlay and analytical hierarchy process (AHP) analyses were used and integrated for efficient evaluation of the determined factors. The proposed approach was implemented in the Antalya province of Turkey, which has great potential for avocado production due to its climatic and environmental conditions. As a result, 602.12 km2 and 653.14 km2 areas were determined to be the most suitable and moderately suitable for avocado cultivation, respectively. Using two MCDA analyses and determining the intersection areas in the site-selection studies would be robust. By using this methodology, suitable lands for avocado cultivation were determined effectively and accurately.

Effects of tic Nanostructured Overlays on D2 Steels by PTA

AbstractTwo metal fillers with TiC nanoparticles (TiC NPs) of less than 100 nm for the overlay process is an alternative to hardfacing for treating surfaces subjected to severe wear. In this work, the effect of tribological behavior for TiC NPs addition on two Co-based filler materials, as well as the dilutions, was studied. Mixtures of Co-based filler metals without and with 0.5% and 2% TiC NPs were deposited onto D2 steel plates using PTA (Plasma Transferred Arc). The BET surface area was 0.17 m2 g-1 and 0.31 m2 g-1, respectively, for Stellite 6 and 12. The distribution of ca 23% macroporous for Stellite 6 was sufficient to get inside the TiC NPs, as well as in the case of Stellite 12, with a pore distribution of ca 13%. Stellite 12 has an increase in the dilutions (70%) and enthalpies showed endothermic reactions. Stellite 6 with NPs was determined to be most effective in increasing the wear resistance.

Analytical study on web deformation by tension in roll-to-roll printing process

Recently, flexible devices have gained high intentions for flexible display, Radio Frequency Identification (RFID), bio-sensor and so on. For manufacturing of the flexible devices, roll-to-roll process is a good candidate because of its low production cost and high productivity. Flexible substrate has a non-uniform deformation distribution by tension. Because the roll-to-roll process carries out a number of overlay printing processes, the deformation affect overlay printing precision and printable areas. In this study, the deformation of flexible substrate was analyzed by using finite element analysis and it was verified through experiments. More deformation occurred in the middle region in the direction parallel to rolling of the flexible substrate. It is confirmed through experiments and analysis that deformation occurs less at the both ends than in the middle region. Based on these results, a hourglass roll is proposed as a mechanical design of the roll to compensate the non-uniform deformation of the flexible substrate. In the hourglass roll, high stiffness material is used in the core and low stiffness material such as an elastic material is wrapped. The diameter of the core roll was designed to be the minimum at the middle and the maximum at both ends. We tried to compensate the non-uniform deformation distribution of the flexible substrate by using the variation of the contact stiffness between the roll and the flexible substrate. Deformation distribution of flexible substrates was confirmed by finite element analysis by applying hourglass roll shape. In the analysis when using the hourglass roll, it is confirmed that the stress distribution is compensated by about 70% and the strain distribution is compensated by about 67% compared to the case using the hourglass roll. To verify the compensation of the non-uniform deformation distribution due to the tension, deformation measurement experiment when using the proposed hourglass roll was carried out. Experiments have shown that the distribution of deformation is compensated by about 34%. From the results, we verified the performance of the proposed.

Study of type-II boundary behavior during SA508-3/EQ309L overlay weld interfacial failure process

Failure behavior of SA508-3/EQ309L overlay weld interface was analyzed. Residual stress measurement showed weld interface was in low stress state at transverse and longitude directions. SA508-3/EQ309L interface was a typical sandwich structure containing a white bright band ended with multi micro-voids type-II boundary. Element changes little around type-II boundary, but hardness varied a lot. The property difference and feature of multi voids made type-II boundary unstable, affecting weld property significantly. Induced shear and tensile tests were applied to study type-II boundary behavior. Under shear stress, type-II boundary suffered work hardening while under tensile stress, type-II boundary cracked first before EQ309L necking. Energy Dispersive Spectrometer (EDS) showed little element variation around type-II boundary. Electron Back-Scattered Diffraction (EBSD) indicated that most part of type-II boundary was ∑3 CSL grain boundary. Under tensile stress, dislocations crossed the boundary, leading to further stress concentration, so as to make the boundary crack under low positive stress.

Multistage manufacturing process control robust to inaccurate knowledge about process noise

A method for robust control of quality errors in a multistage manufacturing process (MMP) is formulated, guaranteeing the product quality even under the worst-case scenario of uncertainties in the knowledge of noise characteristics. Simulations based on the error flow models in automotive cylinder head machining and lithography overlay processes show that the new robust control method increasingly outperforms the traditional stochastic control approach as uncertainties in the knowledge of process noise characteristics increase. It is also shown that controlling MMP quality, while ignoring inaccuracies in the noise model could make quality even worse than if no control is used.

Cost-Effective Performance Management for Washington State Pavement Assets

The Washington State Department of Transportation (DOT) manages 18,230 lane miles (29,332 lane kilometers) of main-line roadway. In the past several years, the Washington State DOT has gone through an evaluation and modification of its pavement management practices. This paper presents the historical perspective on past Washington State DOT pavement practices and several strategies that were developed to improve the management of pavement assets. The Washington State DOT has been successfully preserving the long life of flexible pavements by applying thin hot-mix asphalt (HMA) mill and inlays on the basis of the concept that cracking in thicker HMA sections will primarily be top-down. Furthermore, using the framework developed by the evaluation of cost-effectiveness, several strategies have been implemented to improve the management of Washington State DOT pavement assets. These strategies are ( a) converting 3,000 lane miles (4,827 km) from asphalt to chip seal resurfacing before the year 2025, ( b) planning $850 million to $1.0 billion for rehabilitation and reconstruction for the aging concrete pavement network for the next 10 years with 50% of the concrete slated for reconstruction to be converted to flexible pavement using a crack and seat plus asphalt overlay process, and ( c) applying strategic maintenance to reduce the annual cost by extending the service life of flexible pavements. These cost-effective strategies are expected to generate an overall annual cost savings of $80 million per year by 2025.

PENDEKATAN LOCATION QUOTIENT DAN SHIFT SHARE ANALYSIS DALAM PENENTUAN KOMODITAS UNGGULAN TANAMAN PANGAN DI KABUPATEN BANTUL

Land conversion causes competition in land use, and thus it is necessary to select leading commodities based on agro ecological zoning (AEZ). This study aimed to determine the leading commodities of food crops in Bantul Regency agro ecological zone. This study was conducted on March 2015. The data used was time series data of food crops harvested between 2008-2012 and agricultural commodities zone maps year 2013 based on AEZ with scale 1:50.000 obtained from the Statistics of Indonesia, Agriculture and Forestry Office, and AIAT. Commodities with comparative advantages were analysed by Location Quotient (LQ) while commodities with competitive advantages were analysed by Shift Share Analysis (SSA). Leading food crops commodities were determined through an overlay process using the ArcGIS software covering analysis results of LQ, SSA and agricultural commodities zone maps based on AEZ with scale 1:50.000. The result showed that the wetland paddy is a leading commodity in the study area. Based on comparative and competitive advantages, and compatibility with agricultural commodities zone based on AEZ, wetland paddy is the most leading commodity compared to corn, soybeans and peanuts. It is because of the distribution of this commodity in 10 districts (Sanden, Kretek, Pundong, Bambanglipuro, Pandak, Bantul, Jetis, Banguntapan, Kasihan, and Sedayu) with total area of 11,667 ha or 39.4% of agricultural land in Bantul Regency

On optimizing risk exposures with trend-following strategies in currency overlay portfolios

This paper proposed an optimisation mechanism in the currency overlay portfolios construction process, an area that has not been explored in the literature that tend to focus on pre-determined fixed weights, such as the trading volume of currencies from the survey of the Bank for International Settlement, to construct overlay portfolios and may not always be optimal. This paper optimises the portfolio using the Cholesky Decomposition-based multivariate TVC (Time varying correlation)-GARCH and CC (Constant correlation) GARCH models as allocation schemes, with underlying currencies’ returns originated from a moving average-based trend following single FX strategy in a certain hedging criterion. This paper includes a FX strategy based on the equally weighted (average) of the three different single moving average days to determine hedging needs underlying the hedging criterion. The paper uses the returns of the strategies of EW (equally weighted)-TFX and TFX to construct the optimal currencies overlay portfolios. The findings reveal the EW-TFX portfolios with the TVC-GARCH scheme have the best risk-adjusted portfolio returns. There are some evidences on the significant differences of the portfolios' returns of the EW-TFX overlay portfolios with other currencies portfolios, hence supporting the outperformance. The findings also support existing evidence in the literature.

Developing probabilistic approach for asphaltic overlay design by considering variability of input parameters

Abstract The asphaltic overlay design process considers various input parameters. These parameters are probabilistic in nature, but the current design process adopts deterministic values. This study proposes a comprehensive probabilistic approach for asphaltic overlay design to accommodate the variations in pavement layer thicknesses, pavement layer moduli, vehicle damage factor (VDF), lane distribution factor (LDF) and vehicle growth rate (r). An analytical method, first order second moment (FOSM), is used in developing the proposed design approach. A design example based on real world falling weight deflectometer (FWD) data of a 30 km long highway stretch is worked out to illustrate the proposed design approach. The results indicate that the current deterministic approach estimates an overlay thickness with approximately 95% reliability. Detail analysis of results from the proposed probabilistic approach denotes that choosing marginally lower design reliability could significantly reduce the overlay thickness. A sensitivity analysis of pavement layer moduli indicated that the asphaltic overlay thickness is sensitive to resilient modulus of base layer for fatigue and subgrade layer for rutting. The probability based design approach can accommodate variability of field material properties and construction practices in the asphaltic overlay design process.

Two-layer critical dimensions and overlay process window characterization and improvement in full-chip computational lithography

Edge placement error (EPE) was a term initially introduced to describe the difference between predicted pattern contour edge and the design target for a single design layer. Strictly speaking, this quantity is not directly measurable in the fab. What is of vital importance is the relative edge placement errors between different design layers, and in the era of multipatterning, the different constituent mask sublayers for a single design layer. The critical dimensions (CD) and overlay between two layers can be measured in the fab, and there has always been a strong emphasis on control of overlay between design layers. The progress in this realm has been remarkable, accelerated in part at least by the proliferation of multipatterning, which reduces the available overlay budget by introducing a coupling of overlay and CD errors for the target layer. Computational lithography makes possible the full-chip assessment of two-layer edge to edge distances and two-layer contact overlap area. We will investigate examples of via-metal model-based analysis of CD and overlay errors. We will investigate both single patterning and double patterning. For single patterning, we show the advantage of contour-to-contour simulation over contour to target simulation, and how the addition of aberrations in the optical models can provide a more realistic CD-overlay process window (PW) for edge placement errors. For double patterning, the interaction of 4-layer CD and overlay errors is very complex, but we illustrate that not only can full-chip verification identify potential two-layer hotspots, the optical proximity correction engine can act to mitigate such hotspots and enlarge the joint CD-overlay PW.

The effect of mold materials on the overlay accuracy of a roll-to-roll imprinting system using UV LED illumination within a transparent mold

Although several studies on the roll-to-roll (R2R) imprinting process have reported achieving flexible electronics, improving the alignment accuracy in the overlay process of R2R imprinting is recognized as the biggest problem for the commercialization of this technology. For an overlay technique with high alignment accuracy, it is essential to develop a roll mold with high positional accuracy. In this study, a method for fabricating a roll mold with high positional accuracy is proposed by wrapping a thin glass substrate flexible mold around the transparent roll base, because it can provide higher mechanical strength and thermal stability than a conventional polymer substrate. To confirm the usability of the proposed process, the prepared roll mold was used to fabricate a test pattern of thin-film transistor backplane for a rollable display. The positional and overlay accuracy of the roll mold with the proposed thin glass substrate flexible mold were compared with the roll mold with a conventional polymer substrate flexible mold. Large-area transparent flexible molds with a size of 470 × 370 mm were fabricated by an ultraviolet (UV) imprinting process on thin glass and polyethylene terephthalate substrates, and these flexible molds were wrapped around a roll base of 125 mm radius through a precision alignment process. After an anti-adhesion treatment and the wrapping process, the roll mold with the polymer substrate showed a ~180 μm positional error, whereas the thin glass substrate showed a ~30 μm positional error. After the overlay process using the R2R imprinting system with the alignment system, an average overlay error of ~3 μm was obtained when the thin glass flexible wrapped roll mold was used, whereas a ~22 μm overlay error was obtained when the polymer substrate flexible wrapped roll mold was used.

GTAW Double Torch의 육성용접 공정최적화에 관한 연구

GTAW Double Torch의 육성용접 공정최적화에 관한 연구

LANDSLIDE HAZARD MAPPING ALONG RANTEPAO – PALOPO ROAD SECTION, SOUTH SULAWESI PROVINCE

Rantepao – Palopo Road Section is 61 km long, which provides a connection between Palopo City and North Toraja District. Geographically, the road is winding, located in a hilly area with steep canyon. This condition makes the road vulnerable to soil movement or landslide. On 8 November 2009, a landslide, which caused a huge material and immaterial loss, took place. The scale of the disaster was so large that it was classified as a national disaster. In the landslide disaster management, the mitigation and preparedness effort will be more focused if complemented with spatial data in the form of landslide hazard map in Rantepao – Palopo road section. This research uses Public Works Minister Regulation No.22/PRT/M/2007 concerning landslide hazard area spatial planning as the reference which is modified and assisted with the application of Geographical Information System (GIS). Based on the hydro-morphology condition, the research location can be classified into three, namely typology A (> 1000 mdpl), typology B (500 – 1000 mdpl), and typology C (<500 mdpl). Each typology consists of natural physical aspects with slope indicator, soil type, geology, rainfall, distance from the river/slope water system, distance from seismic fault and vegetation. Human activity aspects comprise planting pattern indicator, slope cutting, pond, population density, and mitigation effort. Based on the regulation, several indicators are difficult to apply in the road section study. Therefore, in this research, some modifications are made to several indicators. In the slope cutting indicator, to obtain slope cutting map, overlay process on topography map, slope variation map, and road section map was performed. The distance from the river/slope water system was obtained by calculating the distance from the river to the road, the closer the river to the road, the bigger the vulnerability. Meanwhile, the distance from the fault was evaluated based on the existence of seismic faults in the research location. Landslide hazard map was obtained by applying overlay process to natural physical aspects map and human activity map. To obtain a hazard map for Rantepao – Palopo road section, a modification by applying overlay to road section map and landslide hazard map was performed. Hazard map on Ranteo-Palopo is divided into three types, i.e. low risk, medium risk, and high risk.

Effects of Anisotropy and Supporting Configuration on Silicon Wafer Profile Measurements for Pattern Overlay Estimation

Wafer geometry and residual stress go through significant changes at different points in the semiconductor manufacturing process flow. Precise wafer geometry measurement is very important to assess process induced wafer geometry change (PIWGC) and minimize pattern overlay in lithography steps of advanced node devices and 3-D (3-dimensional) packaged devices. However, the precise wafer geometry measurement is very difficult due to gravitational wafer sag and interaction between the anisotropy of mechanical properties of Si and wafer supporting configurations. Effects of anisotropy and supporting configuration on 300 mm Si (001) wafer profile measurements were investigated for pattern overlay estimation and process optimization. © The Author(s) 2015. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited. [DOI: 10.1149/2.0011512ssl] All rights reserved.

Site Suitability Analysis For Willow Tree Plantation In Uttarakhand Using GIS

The objective of a present study was to evaluate the land of Uttarakhand for suitability of Willow. The study area located between latitude 28º43'N and 31º27'N and longitude 77º34'E and 81º02'E. and covers approximately 53,485 sq km. A suitability resulting from the overlay process of the identified theme layers has unique information of tree requirement on which the suitability is based. The identified theme layers include temperature (maximum, minimum and average temperature), precipitation and soil texture. All thematic layers with their associated attribute data were encoded in GIS database. Overlay operation was performed on these layers through the model developed using Model Builder module of ARC-view 3.2. The model was a result of the crop requirements and the range of input variables in the state. Model was applied to formulate the suitability classes. The results indicate that 38%, 29.3%, 13.2% and 19.5% area of the total geographical area of the state fall under the most suitable, suitable less suitable and not suitable categories, respectively for Willow plantation. On the basis of the results, it can be recommended that Willow can be grown on the larger area of Uttarakhand state, especially the wastelands can be utilized for cultivation of Willow, which will not only be beneficial for socio-economic point of view but also sequester large amount of the carbon from the atmosphere.

Welding Parameters for Inconel 625 Overlay on Carbon Steel using GMAW

Nickel chromium molybdenum alloys are well known for its creep properties along with high corrosion resistance which finds a very large application in Oil and Petro chemical industries. However due to its prohibitive cost a cheaper alternative of cladding Ni alloys on carbon steel base material is widely used. The Ni alloy may be applied by different methods such as roll bonding, explosive cladding or by weld overlaying. As the weld overlay process is simple and requires a small set up, this is being widely used to improve the corrosion properties of various equipments used in Oil and Petro chemical industries. While the process is simple and easier to apply, enough care need to be applied in controlling the weld chemistry. The most critical element to control is the Fe content in the weld overlay. It is observed that the corrosion properties are not affected when the Fe content is restricted to below 5%. Effort is made in this study to apply the weld overlay using Gas metal arc welding process using soild Inconel 625 wire. Various properties such as chemical composition, cracking tendencies, hardness across the weld overlay area etc were also studied in this work.