bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Electropulsing on the Fatigue Behavior and Change in the Austenite Steel Structure
Authors: Konovalov Sergey V. , Kosinov D.A. , Komissarova I.A. , Gromov V.E.
Published: September 2017

The tests were carried out to identify the influence of electropulse treatment on austenite steel ((mass %) 0.44С, 16.50Mn, 0.26Cr, 0.08Ni, 0.34Si, 2.74Al, 0.002S, 0.017P, Fe – balance). The fa-tigue life is reported to increase by 1.8 times. Electron microscopic research into the dislocation structure of the steel was conducted under diverse fatigue conditions with the purpose to give rea-sons for the identified effect. The dislocation chaos substructure, reticular and fragmented dislocation substructures were found in the steel in the initial state. Fatiguing leads to the change in the dis-location substructure parameters. The subsequent electropulse treatment furthers transformation of the grain structure since grains arise and grow due to evolving local dynamic recrystallization and partial transformation of the dislocation substructure and occurrence of a great number of microtwins. The increase in the fatigue life is associated with the mentioned above transformations resulting from electropulse treatment of the steel structural state.
Modification of Silumin Using the Electroexplosive Method
Authors: Klopotov Anatolii A. , Ivanov Yu.F. , Petrikova E.A. , Gromov V.E. , Kakushkin Yu.A.
Published: September 2017

Surface modification of silumin of the grade AK12 with plasma formed during an electrical explosion of aluminum foil with a sample of yttrium oxide powder placed in the explosion region (the electroexplosive doping method) is carried out. The thermodynamic analysis of the system Al-Si-Y-O is carried out. The phases formed in this system under equilibrium conditions are revealed. Investigations of the elemental and phase composition and the defective substructure are carried out. Mechanical (microhardness) and tribological (wear resistance and friction coefficient) tests of the modified material are performed. The physical mechanisms responsible for multiple enhancement of surface properties of the modified silumin samples are revealed.
The Effect of Sodium Chloride Concentration on Corrosion Resistance of Austenitic Stainless Steel 316L and SMA Weldment
Authors: Rustandi Andi , Setiawan Suganta , Fathurrahman Ihsan
Published: September 2017

Austenitic stainless steel 316L has been widely used in marine environment which containing sodium chloride solution (NaCl). In order to provide matching properties with parent metal, filler metal SMA 316L is commonly produced with slightly over alloyed composition. This work investigated the corrosion behavior of base metal 316L and SMA 316L weld metal by using Electrochemical Impedance Spectroscopy (EIS) to evaluate the mechanism of corrosion behavior based on impedance magnitude measurement at room temperature (27°C ). Various concentrations of sodium chloride solution i.e 1%,2%,3.5%,4% ,and 5% NaCl were prepared. Optical Metallography was also conducted to compare microstructure of base and weld metal. By using Nyquist graphs and its related equivalent circuit parameters showed that impedance magnitude of weld metal was higher which compared to base metal at any NaCl concentration.
Metallography examination revealed that weld metal 316L had dendritic austenitic with delta ferrite and 316L base metal had austenite with typical twin boundaries structure. Higher chromium and nickel content in weld metal 316L was the key variable that control passive film characteristic rather than its microstructure. The lowest impedance magnitude of both 316L and all-weld metal 316L at various concentration was at 3.5% NaCl. Dissolved oxygen at 3.5% NaCl reach maximum solubility which causes severe pitting corrosion.
Fabrication and Characterization of Photocatalyst Coatings by Heat Treatment in Carbon Powder for TiC Coatings
Authors: Guan Su Jun , Hao Liang , Yoshida Hiroyuki , Asanuma Hiroshi , Pan Fu Sheng , Lu Yun
Published: September 2017

Photocatalyst coatings on alumina (Al2O3) balls had been successfully fabricated by mechanical coating technique, with titanium carbide (TiC) powder and subsequent heat treatment in carbon powder. The effect of heat treatment conditions in carbon powder on the formed compounds, surface morphology and photocatalytic activity of photocatalyst coatings was investigated. XRD results show that the formed compounds change with increasing the heat treatment temperature in carbon powder, and rutile TiO2 on the surface of TiC coatings at 1073 K and 1173 K. The generated oxygen vacancies confirmed by XPS measurement, are in favor of narrowing band gap to enhance the visible-light photocatalytic activity of photocatalyst coatings. The photocatalytic activity of photocatalyst coatings has been effectively enhanced, and the samples fabricated at 1073 K and 1173 K for 2 h show higher activity. The fabrication strategy provides us a facile preparation procedure of visible-light responsive photocatalyst coatings.
Shortwave Triboluminescence of Ce Doped Silicate Phosphor in Sliding Friction and its Potential Application as Light Source Means for Controlling Agricultural Pests
Authors: Zhou Qiang , Yang Liu , Xiao Xiao Hong , Zhai Qing Zhi
Published: September 2017

The Ce doped Strontium Magnesium silicate phosphor Sr2MgSi2O7:Ce is compounded by using high temperature roasting process, and the plane sample of prepared phosphor is obtained by tablet press method. A modified MCJ-01A friction tester with the friction pair of glass bar against on the plane phosphor sample is used to determine the triboluminescence property of Ce doped Strontium Magnesium silicate phosphor in the linear contact sliding friction. Examination on the triboluminescence of Ce doped Strontium Magnesium silicate phosphor indicates that a quality triboluminescent phosphor with 448nm± blue spectrum emission can be obtained only in the 1200°C calcining temperature, and only 0.010 molar Ce doping concentration in the Sr2MgSi2O7:Cex can promote the prepared phosphor to generate a higher triboluminecent emission and a smaller full width at half maximum (FWHM). The suitable level of applied load is beneficial to hold a balance between wear increment and spectrum intensity. Finally a triboluminescent unit with squirrel cage structure is constructed to realize the triboluminescence of multiple glass bars against on the cylindrical phosphor in the manner of sliding friction. This can satisfy the light emitting of 360o azimuth, and generate more tribological luminous flux.
Computational Identification of a New Form of Li2MnSiO4 for Battery Applications
Authors: Arsentev Maxim Yu. , Kalinina Marina , Tikhonov Petr , Shmigel Anastasia , Kovalko Nadezhda , Egorova Tatiana
Published: September 2017

The reversibility of phase transformations in Li2MnSiO4 and related materials during charge/discharge of the material is an important factor to enable the practical application of the cathode materials. However, the stability of this material is still unattainable. Here we report the computational identification of a new form of Li2MnSiO4 as a stable candidate with acceptable characteristics. The stability could arise due to the presence of the three-dimensional structure of the inorganic framework. The presence of a structure with a compact unit cell forms the basis for high capacity. Surprisingly it was found to have a stable analogue occurring in nature – Na2CaSiO4 with the same structure. Using this information the possible routes of obtaining such material are presented. The prediction of such material has been not found in the literature previously. Of course the problems such as phase transformations upon delithiation may exist, and to check the data the experimental and computer studies needed.
Glass Fiber/Waste Cotton Fabric Reinforced Hybrid Composites: Mechanical Investigations
Authors: Bodur Mehmet Safa , Bakkal Mustafa , Englund Karl
Published: September 2017

In this study, the hybridization effect on the mechanical properties of the natural fiber reinforced composites was investigated. For this purpose, glass fibers in different ratios of 2.5, 5 and 10 wt% were added in the polymer composites with cotton fibers at the ratios of 12.5 and 25 wt%. In order to have better interfacial bonding and increase the effectiveness of glass fiber on the mechanical properties, maleic anhydride coupling agent was added in the hybrid composite structures. At the end of the study, the best ratios of maleic anhydride, cotton and glass fiber for this kind composites were explored with respect to the economical and mechanical concerns. This study suggests that hybridization can be considered as most promising way to improve the mechanical properties for this novel composite materials.
Evaluation of Mechanical Properties of Aluminum Alloy (Al2024) Reinforced with Silicon Carbide (SiC) Metal Matrix Composites
Authors: Subramanya Reddy P. , Kesavan R. , Vijaya Ramnath B.
Published: September 2017

The investigation of mechanical properties of silicon carbide (SiC) powders reinforced with aluminum alloy composites are recorded in this paper. SiC powders of approximately 35µm size were added in an aluminum alloy matrix to manufacture the samples of ratios 1, 2, 3 and 4 by weight % using the stir casting technique. The specimens were fabricated and several tests were conducted to evaluate the mechanical properties such as tensile strength, hardness and impact strength and then the values are compared with the base alloy. It has been observed from the results that the hardness, impact energy and tensile strength increases with the increase in % of SiC particles until 2% and drops on further increase in the SiC particles.
Synthesis and Characterization Investigations of Laboratory-Synthesized VB-VB2-V3B4 Reinforced Al-7wt.% Si Composites via Mechanical Alloying and Pressureless Sintering
Authors: Mertdinç Sıddıka , Tekoğlu Emre , Gokce Hasan , Agaogullari Duygu , Ovecoglu Mustafa Lutfi
Published: September 2017

In this study, the effect of mechanical alloying (MA) on the microstructural, mechanical and physical properties of vanadium boride particulate reinforced Al-7 wt. % Si matrix composites were investigated. VB-VB2-V3B4 containing vanadium boride hybrid powders were mechanochemically synthesized for 5 h from the V2O5-B2O3-Mg powder blends and leached with hydrochloric acid (HCl) for purification. Laboratory-synthesized VB-VB2-V3B4 powders were incorporated into the Al-7wt. % Si matrix powders with the amount of 2 wt.% via MA for 4h in a SpexTM Mixer/Mill using hardened steel vial/balls with a ball-to-powder weight ratio of 7/1. After the MA process, phase analysis (X-ray diffraction), particle size analysis (laser particle size measurement), surface area analysis (Brunauer-Emmett-Teller measurement) and microstructural characterization (scanning electron microscope (SEM) micrograph) and thermal analysis (differential scanning calorimetry (DSC)) of the non-milled/milled Al-7 wt.% Si-2wt.% (VB-VB2-V3B4) powders were conducted. As-blended and MA’d powders were compacted at a uniaxial hydraulic press to obtain cylindrical compacts with a diameter of 12 mm under a pressure of 400 MPa. Green bodies were sintered at 570°C for 2 h under Ar gas flowing conditions. Microstructural characterizations of the sintered samples were carried out using XRD and optical microscope (OM). Physical and mechanical properties of the composites were investigated in terms of density (Archimedes method), Vickers microhardness and wear rate. The microhardness and wear rate of the 4h of MA’d and sintered sample respectively increased to 0.865±0.256 GPa and 0.0036 mm3/N.m as compared with those of as-blended and sintered sample.
Influence of Long-Term Exposure in the Concrete of FRP Rebars on Bond Characteristics
Authors: Benin Andrey , Semenov Sergey , Bogdanova Ekaterina
Published: September 2017

The current experimental research is devoted to comparison of bond glass fiber reinforced plastic with concrete before and after long-term (quarter year, half year and one year) exposure in the concrete on the air and in the water. The comparative analysis of experimental results was performed.
Determination of Recrystallization Kinetics Model of 30Cr2Ni4MoV Steel Based on Dislocation Density
Authors: Zhou Peng , Ma Qing Xian
Published: September 2017

A new model to predict the structure evolution of 30Cr2Ni4MoV steel is proposed based on the dislocation density in this research. Hot compression of 30Cr2Ni4MoV steel is carried out on Gleeble 1500 at different temperatures from 1233 K to 1473 K with a strain rate of 0.01 s-1 and the deformed samples are immediately quenched by water to frozen the austenite structure. The recrystallization kinetics model of 30Cr2Ni4MoV steel is successfully established by inverse analysis of the flow curve based on the relation between flow stress and dislocation density. In order to validate the proposed model, comparison between the predicted values and experimental values obtained by metallographic analysis is implemented. It is shown that the predicted results agree with the experimental results well.
Characterization of the Tungsten-Steel Functionally Graded Cylinder in Elastic Region
Authors: Ozturk Ali
Published: September 2017

This paper presents how to derive Airy stress function to obtain the thermal stresses in a tungsten-steel functionally graded solid cylinder with fixed ends in elastic region. Once Airy stress function is derived, the thermal stresses can be found due to the related equations. There is uniform heat generation inside the tungsten-steel functionally graded solid cylinder. Material properties of the functionally graded cylinder (FGC) are assumed to vary radially according to a parabolic form and assumed to be independent of the temperature. These properties are yield strength, modulus of elasticity, coefficient of thermal conduction and coefficient of thermal expansion (CTE). Poisson’s ratio is assumed to be constant as an average value between tungsten’s and steel’s. Airy stress function is derived in terms of these properties to characterize the FGC entirely.
A Study on Metallographic Microstructure of Steel Materials Subjected to Fire
Authors: Chi Jen Hao , Peng Peng Chi
Published: September 2017

In view of the fact that construction of modern buildings tends to use a high ratio of iron materials, this study aimed to obtain the ratio of components of steel’s microstructure under different test conditions by heating a A36 steel sheet commonly used in buildings, and applying metallographic replication testing. When the steel sheet was heated above 800°C and then rapidly cooled by water, the ratio of components of the structure were changed dramatically: components such as pearlite disappeared, ferrite was reduced from 90% to a low of 20%, bainite was increased to a maximum of 35%, and martensite was increased to a maximum of 45%. Since the substantial increase of martensite phase in this study led the microstructure of iron material to become thinned out and scattered, the ductility of such material was significantly reduced accordingly, thereby making the steel sheet easily broken. This study expected to provide the test findings of the mechanical behavior and metallographic structure of steel, after being heated to a high temperature and then naturally cooled, to other relevant units of construction engineering to serve as reference for their evaluation of non-destructive testing of steel structures.
Effect of Processing Parameters of Hydrophobic Film on Ceramic Tile
Authors: Prathungthai Prapatsorn , Srilomsak Sutham , Sutapun Wimonlak , Watcharamaisakul Sukasem , Punsukumtana Lada
Published: September 2017

In this research study the fabricated of hydrophobic of SiO2 nanoparticles was modified with tetraethylorthosilicate (TEOS), poly-(dimethylsiloxane) (PDMS) and methyltriethoxysilane (MTES) by using a sol-gel method. The effects of precursors, coating techniques and curing conditions were investigated. A water contact angle (WCA) measurement done using a sessile drop method with an optical contact measuring apparatus. Morphologies of the hydrophobic films were depicted using scanning electron microscopy (SEM). All data were analyzed using Design Expert® software. Results shown that a morphology of hydrophobic films had nanoroughness as evidenced by high contact angle. The largest predicted WCA of these is 150.306 degrees, which will be obtained with a TEOS:SiO2:PDMS:MTES ratio equal to 7.00:3.374:2.75:3.00 wt.% respectively. It is coated using a dipping technique and oven cured at 400°C.
Evaluation of the water and sediment quality of a lotic water-body in the western coastal region of Sri Lanka using Rapid Bioassessment Protocol II (RBP II) of benthic macroinvertebrates
Authors: Wijeyaratne W. M. D. N. , Kalaotuwawe K. M. B. P. P.
Published: September 2017

The biotic indices used in Rapid Bioassessment Protocol II (RBP II) developed by United States Environmental Protection Agency was used to assess the feasibility of using benthic macroinvertebates as bio-indicators for monitoring water and sediment quality in Ja-Ela stream, which is a lotic water body in the western coastal region of Sri Lanka.  Five study sites to cover the entire length of the stream, which are in five different fringing land uses (undisturbed site, agricultural site, industrial discharge receiving site, densely populated urban site and a site close to the mouth of the stream) were sampled  for water and sediment quality parameters and benthic macroinvertebrates from April to October 2015. Shannon-Weiner diversity index (H`), Hilsenhoff Family Biotic index (FBI), Taxa richness (TRI), and Ehemeroptera, Plecoptera and Trichoptera (EPT) index were calculated for each site. Results indicated significant spatial variations in BOD5, COD, visibility, nitrate concentration and total phosphorus concentrations in the water, and total organic carbon content and particle size distribution in sediments. The highest mean values for H' (2.38), TR (13.6) and EPT (6.2) were recorded from the undisturbed site. Significantly higher FBI values are recorded from the industrial discharge receiving site (6.97) and the urban site (6.81), indicating that they are the most polluted sites with higher degree of organic pollution than other sites. These biotic index values showed significant correlations with sediment and water quality characteristics of the study sites (R2 >0.5, p<0.05) The H', EPT, FBI and TR values for benthic macro-invertebrate community showed that the upstream portion of this stream is habitable to pollution sensitive taxa, while the downstream areas close to its opening to Negombo estuary are habitable by pollution tolerant taxa. Results of the present study identified the RBP II as a possible bio monitoring protocol to reflect the water and sediment quality in the Ja-Ela stream.
Multi-mesh gillnet selectivity of Oreochromis mossambicus and O. niloticus (Cichlidae) in the fishery of three large perennial reservoirs in Sri Lanka
Authors: Jayasinghe R.P.P.K , Amarasinghe U.S. , Moreau J.
Published: September 2017

Erratum
Thermal warpage measurement system for environmental test of automotive devices
Authors: Ishihara Mitsuhiro
Published: September 2017

As automotive semiconductor market has expanded, the importance of measurement of temperature-dependent warpage (thermal warpage) has been increasing. For automobiles, high reliability is necessarily demanded because their failures are directly linked to people's life. Therefore automotive industry had established AEC qualification standards for automotive devices. The standard demands environmental tests that include not only high temperature test but also negative temperature test reaching -55 â„ƒ. In view of this situation, we have developed a thermal warpage measurement system that has the ability to change sample temperature from -60 to 260 â„ƒ which can meet the demands of the standard. The following are some features of the system. <(1)Warpage measurement ability>Measurement is performed by confocal method which is well known as accurate optical metrology. Generally speaking, confocal method is time consuming method for measurement. But our technique we call non-scanning confocal method overcomes such a drawback maintaining advantages of confocal method and the non-scanning confocal method has already been used widely for in-line coplanarity inspection of flip-chip bumps. Conventional warpage measurement technique like Moire method needs sample preparation like de-ball and painting. But the non-scanning confocal method doesn”™t need any sample preparation. The method can measure not only substrate warpage accurately without de-ball but even ball height/coplanarity. Moreover the system can deal with even several tens of micron diameter bumps, because it has 8.0um pixel resolution regardless of sample size. Unlike conventional warpage measurement system, the field of view (FOV) size of 13x13mm is constant and bigger samples than the FOV can be measured by stitching FOVs using a XY translation stage up to 136x323mm (JEDEC tray size).<(2)Heating and cooling ability>The system has a big size chamber for heating and cooling so that a whole JEDEC tray can be measured. In order to heat all samples in the big chamber uniformly, convection heating is used as heating method. Convection heating has many advantages compared to radiation heating that is normally used by conventional systems. The advantages are as follows.
RDL Multilayer Metallization Approaches for TGV
Authors: Keusseyan Roupen , Mobley Tim , Young-Dohe Elizabeth
Published: September 2017

Significant advances have been accomplished in the field of Through Glass Via (TGV) technology; enabling a new generation of electronic designs that achieve higher performance, while leveraging low cost system solutions. Through-hole creation methods in glass have been optimized for mass production with consistent via diameter, shape and wall chemistry/morphology. This has enabled the development of unique copper via metallization materials that exhibit very high conductivity, thermal expansion matching and hermeticity. This paper will discuss post via metallization processes for multilayer RDL (Redistribution Layer) metallization on both sides of the glass wafer. Unique Chemical Mechanical Polishing (CMP) development approaches for glass wafers with copper thick film vias will be explained. Thin film deposited adhesion layer on glass, followed by a deposited metallization layer will be described. Types of deposited adhesion layer on glass for optimized adhesion and electrical contact with the vias will be examined. Furthermore, copper plating approaches for higher conductivity and fine line circuit patterning are examined. Polymeric dielectric material systems for multilayer RDL on both sides of the glass will also be reviewed.
Cost Comparison of Fan-out Wafer Level Packaging and Flip Chip Packaging
Authors: Lujan Amy
Published: September 2017

In recent years, there has been increased focus on fan-out wafer level packaging with the growing inclusion of a variety of fan-out wafer level packages in mobile products. While fan-out wafer level packaging may be the right solution for many designs, it is not always the lowest cost solution. The right packaging choice is the packaging technology that meets design requirements at the lowest cost. Flip chip packaging, a more mature technology, continues to be an alternative to fan-out wafer level packaging. It is important for many in the electronic packaging industry to be able to determine whether flip chip or fan-out wafer level packaging is the most cost-effective option.

This paper will compare the cost of flip chip and fan-out wafer level packaging across a variety of designs. Additionally, the process flows for each technology will be introduced and the cost drivers highlighted. A variety of package sizes, die sizes, and design features will be covered by the cost comparison. Yield is a key component of cost and will also be considered in the analysis.

Activity based cost modeling will be used for this analysis. With this type of cost modeling, a process flow is divided into a series of activities, and the total cost of each activity is accumulated. The cost of each activity is determined by analyzing the following attributes: time required, labor required, material required (consumable and permanent), capital required, and yield loss.

The goal of this cost comparison is to determine which design features drive a design to be packaged more cost-effectively as a flip chip package, and which design features result in a lower cost fan-out wafer level package.
A Wireless Hay Bale Status Sensor Suite Using PCB Sensor Technology
Authors: Craven Jeff D. , Muscha Andrew W. , Harrison R. Chase , Kreitzer Markus A. R. , Dean Robert N. , Guertal Beth A.
Published: September 2017

The spontaneous combustion of curing hay bales poses serious safety and financial issues to farmers and ranchers across the United States and abroad. The primary cause of this spontaneous combustion is the baling of hay before it has adequately dried and reached a sufficiently low moisture content level. This inadequate drying is primarily due to the farmer allowing the hay to dry in the field after cutting for a given period of time. But unfortunately, this does not always ensure that the hay has sufficiently dried before baling. Spontaneous combustion of hay bales is due to a proliferation of thermophilic bacteria that thrive in a moist and hot environment. If the moisture content of hay is greater than 20%, it provides a suitable environment for mesophilic bacteria, which can heat the hay to as a high as 140°F. Although this is not problematic in and of itself, a 140°F hay bale is a suitable environment for the proliferation of thermophilic bacteria, which can further heat the hay to 170oF. At this temperature, the hay can spontaneous combust, destroying the hay and risking the loss of buildings, equipment, livestock and agricultural workers. To combat this problem, a low-cost, low-power, wireless hay bale status sensor suite has been developed so that the farmer can easily and safely monitor the conditions inside a curing hay bale, to give the farmer time to take action before the bale spontaneously combusts. The battery operated sensor suite has two sensors in contact with the hay inside the bale, a printed circuit board (PCB) moisture content sensor and a discrete temperature sensor. The extremely low-cost of the PCB moisture content sensor is what enables the practicality of the sensor suite. WiFi is used to transmit moisture content and temperature data to the farmer's smartphone when it comes within range. The sensor suite is placed inside the bale at the time of baling. After the bale has fully cured, in four to six weeks, the reusable sensor suite can be removed and used in a new bale.
New Wafer Level Packaging Concept for Power LEDS
Authors: Volpert Marion , Soulier B. , Peray P. , Ait-Mani N. , Gasse A. , Henry D. , Tallet C. , Beix V. , Aboulaich A. , Zheng-Sung C. , Diot J. L.
Published: September 2017

The demand for more efficient, cheaper, and smarter lighting system is ever increasing. Today it is well accepted that solid state lighting using high brightness LEDs is the leading technology for these lighting applications. LEDs has established itself as the solution for a large variety of applications such as street lighting, households, professional buildings etc… The growing need and incredible market for such lighting system drive the research for solutions on the cutting edge of the technology. However if the effectiveness of 2D GaN devices does not need to be proven any more, some reliability issues may arise due to difficult thermal management, proper encapsulation, good color control. Indeed one of the leading factor to improve LEDs devices as well as to reduce the price is to work on the packaging. How the interconnections or encapsulations are achieved, how the color conversion is done, or how is the heat generated handled.

The main technology for LEDs fabrication is the growth of 2D GaN over sapphire substrates. Today some of the most widely spread configurations for these 2D LEDs are common chips (CC) and vertical thin film chips (VTF). In both cases the electrical contact is achieved by gold wires and in this configuration, in addition of the wire bonding step, the useful area for light emission is decreased because of the shadowing made by the metallic grid and the bonding pad surfaces. The flip chip (FC) configuration is also available in the LED manufacturing and looks promising as it achieves smaller size package and higher current. However, in this configuration the process remains complicate, as it needs an additional step for removing this growing substrate, the main technique today consisting on the Laser Lift Off (LLO).

In this paper we present a novel approach to achieve promising LED devices. The new packaging approach uses the fabrication of nanowires over a silicon substrate, and some wafer level packaging to achieve the wires encapsulation and fabricate the P and N interconnections, using Through Silicon Vias (TSV). The silicon wafer level fabrication process achieves the possibility to use standard microelectronic equipment for the LED fabrication and its packaging. For this device specific silicon technologies are developed, such as wafer bonding and thinning, high aspect ratio TSV-last. Once fabricated the chip LEDs are diced and mounted on a specifically designed QFN which is itself directly mounted on a luminaire. The specific QFN is designed to achieve simultaneous reflow of many LEDs chips, and to properly handle the thermal management over the lifetime of the device. For test purposes and to characterize the electro-optical performances as well as some thermal resistances the LEDs are also mounted on a starboard. This new fabrication and packaging approach looks promising, and the specific technologies developed as well as the main characterization results will be presented.
Transient Liquid Phase Sintering Pastes in Heterogeneous Integration
Authors: Shearer Catherine
Published: September 2017

Integrated package technologies continue to be the dominant trend in the electronics packaging industry. In particular, heterogeneous integration of logic and memory or sensing is an enormous growth segment for both mobile electronics and IoT applications.

In the mobile microprocessor segment of the field, the most advanced technologies will be implemented in the early adopter class. New package architectures and interconnect schemes will be vetted and implemented without significant cost pressure, performance is the driver.

In the IoT segment and downstream mobile, however; lower cost alternatives to cutting edge packaging architectures are needed to drive market growth. Sintering pastes offer an opportunity to cost-effectively enable cutting edge 3D package capability for a wider variety of applications.

In this paper we will explore the use of transient liquid phase sintering (TLPS) pastes in package-on-package (POP) schemes for integrated logic with memory or sensing functions in through mold via architectures. Through mold via technology has been well established in the industry and has significantly contributed to the adoption of three dimensional packaging architectures. The advantages of using TLPS pastes in similar structures will be detailed.
Advanced Packaging Lithography and Inspection Solutions for Next Generation FOWLP-FOPLP Processing
Authors: Silveira Elvino Da , Best Keith , Singh Gurvinder , McCleary Roger
Published: September 2017

For more than 50 years the semiconductor industry has pursued Moore's law, continuously improving device performance, reducing cost, and scaling transistor geometries down to where advanced CMOS has reached beyond the 10nm technology node. The commensurate increase in I/O count has created many challenges for device packaging which hitherto was considered low cost with simple solutions. It was once thought that old backend foundry lithography steppers could be used to address the new packaging requirements; which was true whilst the substrates remained in the traditional 300mm Silicon format. The recent unprecedented rapid growth in Fan Out Wafer Level Packaging (FOWLP) applications has introduced a more complicated landscape of process challenges, with no restriction on substrate format, where cost is the main driver and high yields are mandatory.

This paper discusses the lithography process challenges that have ensued from disruptive FOWLP, and more recently the paradigm shift to Panel fan out Packaging. The work reports on lithography solutions for CD control over topography and high aspect ratio imaging of 2μm line/space RDL. In addition, the introduction of new inspection capabilities for defects and metrology is reported for both wafers and panels. The increase in lithography productivity and cost reduction provided by FOPLP is also discussed with production examples.
Cu Pillar, RDL and Via Fill Challenges facing FOWLP
Authors: Gongora Eric , Najjar Elie , Richardson Thomas , Linehan Leo , Commander John
Published: September 2017

The mobile market continues to push the limits of performance (electrical, power, thermal) and size. This paralleled with the challenges faced with continued wafer node reductions is driving the need for “More than Moore” through advanced vertical integration. One package form factor that has risen to meet these challenges and is being adopted by several end applications is the Fan Out Wafer Level Package (FO-WLP). This package is a modified version of standard Wafer Level Packages that provides a higher level of integration with an increased amount of I/Os. A variety of FOWLP packaging schemes are offered in the market (eWLB, InFO, SWIFT, etc.), each containing their own set of technical challenges (die first, die last, single RDL, multiple RDL layers, etc..). These challenges drive the need for optimized Cu, Sn, SnAg and Ni plating solutions for each package architecture, end application, die layout, plating tool, pillar construction, etc.. This presentation reviews the progression of Cu Pillars/Bumps, Redistribution Layers, and via fill requirements and how performance chemistry is being developed to meet these individualized needs.
Gut Microbiota’s Effect on Mental Health: The Gut-Brain Axis
Authors: Clapp Megan , Aurora Nadia , Herrera Lindsey , Bhatia Manisha , Wilen Emily , Wakefield Sarah
Published: September 2017

The bidirectional communication between the central nervous system and gut microbiota, referred to as the gut-brain-axis, has been of significant interest in recent years. Increasing evidence has associated gut microbiota to both gastrointestinal and extragastrointestinal diseases. Dysbiosis and inflammation of the gut have been linked to causing several mental illnesses including anxiety and depression, which are prevalent in society today. Probiotics have the ability to restore normal microbial balance, and therefore have a potential role in the treatment and prevention of anxiety and depression. This review aims to discuss the development of the gut microbiota, the linkage of dysbiosis to anxiety and depression, and possible applications of probiotics to reduce symptoms.
Responses of phytoplankton functional groups to environmental factors in the Maixi River, southwest China
Authors: Huang Guojia , Li Qiuhua , Wang Xiaoqing , Han Mengshu , Li Lei , Xiao Jing , Liu Yipeng
Published: September 2017

The functional groups approach is an efficient way to analyze seasonal changes in phytoplankton biomass as it is based on the physiological, morphological, and ecological attributes of the species. In this study, we identified the functional groups and driving factors behind short-term succession in phytoplankton communities. We analyzed physical, chemical, and biological factors of the Maixi River in Baihua Reservoir (BHR) from August to September, 2013 (summer, phase I) and March to May, 2014 (late spring and early summer, phase II). The 226 samples collected were divided into 23 functional groups. In phase I, phytoplankton biomass ranged from 4.88 to 30.59 mg·L-1, and the group S1 (Pseudanabaena limnetica) had the greatest biomass. In phase II, phytoplankton biomass ranged from 2.22 to 50.61 mg·L-1, and groups Y (Cryptomonas sp.) and S1 (P. limnetica) had the greatest biomass. Dominant functional groups in the Maixi River changed from S1 + D + Y + Lo in phase I to Y + S1 in summer. Changes in the phytoplankton community varied between 0 and 0.144 day-1 in phase I and between 0.008 and 0.389 day-1 in later spring and early summer. This showed a steady-state phytoplankton community during the two phases, in which the functional groups S1 (P. limnetica) and Y (Cryptomonas sp.) were dominant. Pseudanabaena limnetica, Synedra sp., Peridinium sp., and Cryptomonas sp. were dominant during summer, contributing to 70% of the total biomass in the steady-state community, and P. limnetica, Synedra sp., Cryptomonas sp., and Chlamydomonas sp. were dominant during later spring and early summer, contributing to 60% of the total biomass in the community. Groups S1, D, and Y formed easily in the Maixi River, but P. limnetica was the dominant species in the eutrophic conditions of the Maixi River. According to biotic and abiotic factors, we concluded that the Maixi River is hypertrophic, and water resource management should take blooms of P. limnetica occurring in May into account. Temperature and dissolved oxygen were the critical factors affecting the steady-state of the phytoplankton community in late spring and early summer and summer, respectively. Because the Maixi River is an important source in the BHR, its phytoplankton functional groups directly affect the ecological balance of the water environment.
Assessing the impact of road transport infrastructure investment on economic development in South Africa
Authors: Hlotywa Anathi , Ndaguba Emeka A.
Published: September 2017

Background: There has been considerable decline in the investment on road transport infrastructure in recent times, as a result of the dwindling economic investment owing to lowering gross domestic product (GDP) since 2009.Objective: The objective of this study was to examine the relationship between road transport investment (ROTI) and economic development (ED) in South Africa. This article adopts the Harrod–Domar (HD) model of economic growth and development theory, endogenous growth theory and Solow–Swan neoclassical growth model.Method: Data were derived from the South African Reserve Bank, Quantec database and Statistics South Africa (StatsSA) between 1990 and 2014. It used time series, econometric models cointegration and vector error correction model (VECM) to analyse.Result: The results of the estimation demonstrate that the explanatory variables account for approximately 86.7% variation in ED in South Africa. Therefore, there exists a positive relationship between ROTI and ED.Conclusion: This study established a long-run relationship between phenomena and demonstrates the role of road transport investment on economic development in South Africa.
Christian mission agencies and the question of slavery in German Cameroon, 1884-1916
Authors: Lang Michael Kpughe
Published: September 2017

Mission agencies claimed to exhibit enlightenment motifs of progress, liberty, civilization and unity of humanity. This amounted to a paradoxical association between the mission agencies and the anti-slavery campaign in Africa like elsewhere. In German Cameroon, Catholic and Protestant missions engaged in the battle against slavery, while at the same time colluding with the colonial government to perpetuate it in transformed ways. Expectedly, as German missions took measures to surmount slavery, they surprisingly peddled its perpetuation in diverse ways. This paper critiqued the involvement of mission agencies in the campaign against slavery in German Cameroon from 1884 when Germany annexed the territory to 1916 when her imperial rule was forcibly terminated. It opened with an introductory background that contextualizes the mission-slavery question connection. This is followed by an examination of the efforts of the missions in fighting slavery in Cameroon. The paper further discussed missions’ dependence on indigenous converts in carrying out their numerous activities, along with their complicity with the colonial government in enslaving and exploiting Cameroonians in ways that were beneficial to the German colonial enterprise. The paper therefore submitted that German missions’ battle against slavery was bedevilled by the fact that they gave significant importance to the imperial designs of their government, with little commitment to improving the wellbeing of Cameroonians. Little wonder colonial and missionization exploitation which is inseparable from the modern understanding of slavery was at its highest during the German era.Keywords: German Cameroon, German missions, slavery
A manual beaming device: an improved method for warp winding in broadloom weaving
Authors: Frimpong Charles , Seidu Raphael Kanyire , Agyei Petra Ama
Published: September 2017

Challenges with broadloom beaming that affect the weaving process and eventually the woven fabric aspect, could be as a result of the great bulk of yarns attached to the weighted box for tensioning. This project sought to construct a beaming device that maintains even tension of warp yarn at beaming by reducing the amount of yarns held together in a group to the weighted box. The study employed the Universal Research Methodology (URM). Results from interviews and observations, aided in constructing an appropriate device for beaming. In the study, relevant data was solicited from textile students and technicians at the textile section of the Industrial Art Department of Kwame Nkrumah University of Science and Technology which aided in designing the blueprints. The outcome of the study after 14 beaming revealed that challenges and faults hitherto encountered at beaming and weaving were largely absent. The study recommends the adaptation of this new mechanism and method of warp attachment to ensure smoother weaving and enhanced fabric quality.Keywords: Broadloom Weaving, Warp Preparation, Manual Beaming, Beaming Device, Tension Differentials
Determinants of condom use among currently married men in Zambia
Authors: Thankian Kusathan , Mwaba S.O.C. , Jere-Folotiya J , Hapunda G , Menon A.J.
Published: September 2017

HIV is one of the leading health threats and cause of morbidity and mortality in Zambia. Among many preventive measures, condom use is the most effective methods of preventing HIV. The aim of this study was to investigate factors associated with condom use among currently married men in Zambia. Secondary data from the 2013 Zambia Demographic Health Survey was used. Results from binary logistic regression analysis showed that condom use is associated with being young (β = -0.71, p < 0.001), being rich (β = 0.25, p < 0.05), paying for sex (β = 0.42, p < 0.001), perceiving risk of contracting HIV (β = 0.38, p < 0.001), and believing in the efficacy of condom use as a protective measure against HIV (β = 0.24, p < 0.01). Condom use in Zambia is associated with socio-demographic characteristics and habits of adult males. Therefore, prevention measures aimed at increased the use of male condoms should integrate social demographic characteristics and habits of adult males to be effective.Keywords: Condom use, married men, determinants, Zambia
Primary factors threatening survival of SMEs in Mozambique
Authors: Alen Sawaya , Bhero Shepherd
Published: September 2017

There is no dispute that entrepreneurship is critical for spurring entrepreneurs into launching small businesses to solve the perennial problem of youth unemployment. The prevailing viewpoint has therefore postulated on the fact that only the lack of entrepreneurship is to blame for the observed paucity of business start-ups to address the scourge of unemployment in Mozambique. This paper is based on a research that was carried out in Greater Maputo, the capital of Mozambique, involving a sample of 485 SMEs chosen using random sampling strategy. A face to face interview was conducted using structured, close-ended questionnaires to collect the primary data. The research was carried out applying quantitative methodology, using descriptive statistics and inferential research design, emphasising on frequencies and percentages as  instruments of data management. The study revealed that the main problem of the start-up, growth and sustainability of SMEs was in fact inadequacy in competitiveness rather than the lack of entrepreneurship per se. The paper therefore offered recommendations on the appropriate solutions of encouraging the spirit of competitiveness within SMEs so as to deal with the scourge of youth unemployment in Mozambique.Keywords: Competitiveness, Entrepreneurship, small and medium enterprises, SMEs
Monitoring shipping emissions in the German Bight using MAX-DOAS measurements
Authors: Seyler André , Wittrock Folkard , Kattner Lisa , Mathieu-Üffing Barbara , Peters Enno , Richter Andreas , Schmolke Stefan , Burrows John P.
Published: September 2017

Abstract. A 3-year time series of ground-based multi-axis differential optical absorption spectroscopy (MAX-DOAS) measurements of NO2 and SO2 on the island Neuwerk has been analyzed for contributions from shipping emissions. The island is located in the German Bight, close to the main shipping lane (at a distance of 6–7 km) into the river Elbe towards the harbor of Hamburg. Measurements of individual ship plumes as well as of background pollution are possible from this location. A simple approach using the column amounts of the oxygen molecule dimer or collision complex, O4, for the determination of the horizontal light path length has been applied to retrieve path-averaged volume mixing ratios. An excellent agreement between mixing ratios determined from NO2 retrievals in the UV and visible parts of the spectrum has been found, showing the validity of the approach. Obtained mixing ratios of NO2 and SO2 are compared to co-located in situ measurements showing good correlation on average but also a systematic underestimation by the MAX-DOAS O4 scaling approach. Comparing data before and after the introduction of stricter fuel sulfur content limits (from 1 to 0.1 %) on 1 January 2015 in the North Sea Emission Control Area (ECA), a significant reduction in SO2 levels is observed. For situations with wind from the open North Sea, where ships are the only local source of air pollution, the average mixing ratio of SO2 decreased by a factor of 8, while for NO2 in the whole time series from 2013 to 2016, no significant change in emissions was observed. More than 2000 individual ship emission plumes have been identified in the data and analyzed for the emission ratio of SO2 to NO2, yielding an average ratio of 0.3 for the years 2013/2014 and decreasing significantly, presumably due to lower fuel sulfur content, in 2015/2016. By sorting measurements according to the prevailing wind direction and selecting two angular reference sectors representative for wind from the open North Sea and coast excluding data with mixed air mass origin, relative contributions of ships and land-based sources to air pollution levels in the German Bight have been estimated to be around 40 % : 60 % for NO2 as well as SO2 in 2013/2014, dropping to 14 % : 86 % for SO2 in 2015/2016.