bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation and Suppression of Microcystis aeruginosa by Photocatalyst Coatings with Visible Light Photocatalytic Activity
Authors: Guan Su Jun , Hao Liang , Hirakawa Yutaka , Yoshida Hiroyuki , Amano Yoshimasa , Machida Motoi , Lu Yun
Published: September 2017

Photocatalyst coatings had been successfully fabricated by molten salt treatment at 673 K for 3 h for titanium (Ti) coatings, which coated on alumina (Al2O3) balls by mechanical coating technique with Ti powder. The influence of molten salt treatment on the formed compounds, surface morphology and photocatalytic activity under visible light irradiation on degradation of MB solution and suppression of Microcystis aeruginosa of photocatalyst coatings was investigated. XRD results show that potassium titanate (K2Ti6O13) forms on the surface of Ti coatings during molten salt treatment. The visible light photocatalytic activity of photocatalyst coatings has been effectively enhanced by molten salt treatment.
The Stability and Hydrogen Adsorption Properties of Ti Doped Superatomic-Al12C Cluster
Authors: Wu Xue Ke , Zhang Song , Yue Li , Jing Tao
Published: September 2017

The structural stability, metallicity and hydrogen adsorption properties of Ti doped superatomic-Al12C cluster have been investigated by first-principles based on density functional theory. The results show that the structural stability of Al12C has been enhanced after replacing the central Al atom of icosahedra Al13 configuration by carbon atom, and the most stable structure and stability of Al12CTi and the lowest energy structures of Al12CTi (H2)n (n=1-8) are searched and discussed. Moreover, the Al12CTi (H2)6 not only exhibits strong stability according to HOMO-LUMO energy gap analysis, but also absorbs six hydrogen molecules in the absorb energy range of physical and chemical absorption, which could be considered as a candidate for hydrogen absorption materials development.
The Aggregation Study and Characterization of Silver Nanoparticles
Authors: Chowdhury Silvia , Yusof Faridah , Sulaiman Nadzril , Faruck Mohammad Omer
Published: September 2017

In this article, we have studied the process of silver nanoparticles (AgNPs) aggregation and to stop aggregation 0.3% Polyvinylpyrrolidone (PVP) was used. Aggregation study carried out via UV-vis spectroscopy and it is reported that the absorption spectrum of spherical silver nanoparticles were found a maximum peak at 420 nm wavelength. Furthermore, Transmission Electron Microscopy (TEM) were used to characterized the size and shape of AgNPs, where the average particle size is around 10 to 25 nm in diameter and the AgNPs shape is spherical. Next, Dynamic Light Scattering (DLS) were used, owing to observed size distribution and self-correlation of AgNPs.
Study on the Recrystallization of Deformation Microstructure of AZ31 Magnesium Alloy
Authors: Lou Yong Ping , Chen Ming , Li Jun Feng , Hu Xiao Dong
Published: September 2017

A real-time calculation model discretized by the cellular automata (CA) method was developed for the numerical simulation of AZ31 magnesium alloy microstructure evolution during recrystallization (RX). The RX processes under different strains were simulated, also, variations in morphologies of recrystallization grains are discussed. The results of numerical simulation were compared with those of experiment analysis, and the microstructure obtained by CA was found to well agree with the actual pattern obtained by EBSD (Electron Backscattered Diffraction) analysis. The numerical simulation technique provides a flexible way of predicting the recrystallization of deformation microstructure evolution.
The Study of Solidification Behavior in Cast Irons Using the Linear Displacement Method
Authors: Boonmee Sarum , Chuencharoen Lertrit
Published: September 2017

This study aims to assess the solidification shrinkage and expansion during the solidification of cast irons. The solidification shrinkage and expansion in cast irons are due to the formation of austenite and graphite respectively. In this study, the linear displacement method was used to observe the solidification event combined with the cooling curve analysis. It was found that the cooling and displacement curves show good correlations in time of events during solidification. The displacement due to graphite expansion increased with the carbon equivalent. The linear expansion of 0.2 to 1.9 mm was observed for the carbon equivalents ranged from 3.7 to 4.5. On the other hand, the displacement due to the austenite shrinkage was found to decrease with increasing carbon equivalents.
Tool Wear of Aluminum/Chromium/Tungsten/Silicon-Based-Coated End Mill Cutters in Milling Hardened Steel
Authors: Wada Tadahiro , Hanyu Hiroyuki
Published: September 2017

In turning hardened steel, polycrystalline cubic boron nitride (cBN) compacts are widely used, due to their high hardness and high thermal conductivity. However, in milling hardened steel, fracture of cBN cutting tools readily occurs because they have poor fracture toughness. Therefore, coated cemented carbide tools, which have good fracture toughness and wear resistance, are generally and widely used. In this study, hardened steel (ASTM D2, JIS SKD11, 60HRC) was milled with three physical vapor deposition coated cemented carbide end mill cutters in order to determine effective tool materials for milling hardened steel. The coating films used were two types of aluminum/chromium/tungsten/silicon-based-coating films and (Ti,Al)N-coating film. The two types of aluminum/chromium/tungsten/silicon-based-coating films are a new type of coating film, and the Type I and Type II coating film was a two-layered and multi-layered structure, respectively. The following results were obtained: (1) In milling hardened steel at a cutting speed of 2.5 m/s, Type II coating film was the best coating material among the three types of coated film. Type I coating film was superior to (Ti,Al)N-coating film. (2) The critical scratch load of both Type I and Type II of over 130 N became larger than that of the (Ti,Al)N-coating film of 65 N. (3) The multi-layered structure is expected to improve the tool life.
The Application and Performance of Diamond and PCBN Tools in Difficult-to-Cut Materials
Authors: Zhou Yu Hai
Published: September 2017

Diamondand PCBN are extra-hard materials. There are several grades in the PCD andPCBN groups. Comprehensive Review of Super hard materials such as diamond cutting tools, high-speed machining PCBN tool and performance, the type of domestic and international manufacturing and research status . Elaborate on three high-speed machining with a diamond cutter nature and characteristics of the domestic and foreign manufacturing enterprise status, as well as polycrystalline cubic boron nitride tool features and applications. The isotropic synthetic graphite high-speed processing of diamond tool applications, engine block, cylinder heads high-speed milling PCBN cutting tool applications, aerospace application example to illustrate the advantages of hard material tool in high-speed machining of titanium alloys in high speed turning PCBN tools. Hard material tool to provide guidance and support for the selection of high-speed processing manufacturing enterprises.
Multiscale modeling of transport in silicon heterojunction solar cells
Authors: Muralidharan Pradyumna , Goodnick Stephen M. , Vasileska Dragica
Published: September 2017

Silicon based single junction solar cell technology continued to make significant strides in the past year with new world record module efficiencies being reported for the Panasonic heterojunction with thin intrinsic layer (HIT) module (23.8%) and the SunPower rooftop silicon module (24.1%). The HIT cell which is comprised of amorphous silicon (a-Si) and crystalline silicon (c-Si) currently holds the world record efficiency (25.6%) for a silicon based single junction solar cell. Further improvement in this technology requires a rigorous understanding of the underlying physics of the device.

The device performance of a-Si and c-Si heterojunction solar cells depends heavily on the nature of transport at the hetero interface and defect assisted transport through the a-Si. Different microscopic processes dominate transport in different regions of the device and take place across widely varying time scales. In this work we present a multiscale model which utilizes different simulation methodologies to study physics in various regions of the device, namely, the Ensemble Monte Carlo (EMC), Kinetic Monte Carlo (KMC), and Drift Diffusion (DD) solvers. The EMC studies the behavior of the photogenerated carriers at the heterointerface; the KMC analyzes transport of the photogenerated carriers through the intrinsic amorphous silicon (i-a-Si) barrier layer; and the DD solver calculates current and other device properties in the low field regions of the cell. These solvers are then self consistently coupled to analyze device performance. Previously, our KMC simulations have shown that hopping is the main mode of transport through the i-a-Si, and the photogenerated carries are collected by defect emission rather that Poole - Frenkel emission or direct tunneling1. In addition, using EMC simulations we have shown that the photogenerated carriers exhibit non Maxwellian behavior at the heterointerface2.

This work specifically describes the self-consistent coupling of the DD and EMC solvers. By adding the EMC solver to the multiscale solver we are able to capture the high field behavior of the photogenerated carriers, and its affect on device parameters such as JSC, VOC, FF and efficiency.
Minimizing Film Stress and Degradation in Thin-Film Niobium Superconducting Cables
Authors: Gupta Vaibhav , Sellers John A. , Ellis Charles D. , Yelamanchili Bhargav , Zou Simin , Cao Yang , Tuckerman David B. , Hamilton Michael C.
Published: September 2017

The future of superconducting and cryogenic electronic systems can significantly benefit from densely integrated superconducting multi-layer and multi-signal flexible cables due to the massive number of electrical interconnects needed in systems such as superconducting quantum computers and cryogenic detector arrays. In order to maintain superconductivity in niobium (Nb) thin films, film stress and degradation must be minimized. We are working towards configurations with embedded traces, where it is expected that the superconductor material will be subjected to subsequent fabrication steps that must not degrade the properties of the superconductor. We previously observed degradation of the superconducting properties of Nb, such as reduction of both transition temperature and critical current, as a result of curing a polyimide passivation layer at supplier recommended curing temperature (350 oC). The deterioration in the superconducting properties may be due to mechanical stress in the film or diffusion of impurities into the Nb during the curing process

Film stress plays a vital role in the superconducting properties of Nb. Previous research by other groups has focused on in situ ion bombardment, substrate fixturing and wafer preparation in order to minimize film stress. In this work, we discuss the role of argon (Ar) pressure and power during Nb sputtering on the quality of Nb and Nb/Al thin films. By varying the Ar pressure and applied power during sputter deposition, we have produced both tensile and compressive films on flexible substrates in order to find the pressure that yields a near zero stress Nb and Nb/Al thin film at room temperature. A low stress Nb film was tested with a thin Al barrier layer (of the order of 10's of nm) between Nb and polyimide to protect the Nb superconductivity during the PI curing step. Nb traces with a thickness of roughly 250nm and a width of 50um were used for this work. Nb films deposited at different Ar pressures and power levels were tested for critical transition temperature (Tc), critical current (Ic), and sheet resistance (Ω/□), to compare the superconducting behavior of different Nb films. Details of the fabrication processes, experimental procedures and performance results will be presented. This work will help determine materials stacks-ups that may be useful for future multi-layer Nb-based flexible superconducting cables.

Acknowledgment: We gratefully acknowledge financial support and technical guidance from Microsoft Research for this work.
3D Modular Power Electronic Packages and Modules for different power classes - from 50W to 50kW
Authors: Böttcher Lars , Karaszkiewicz S. , Manessis D. , Ostmann A.
Published: September 2017

This paper will describe the use of embedded die technologies for various application fields. The main focus of the paper will be the development work within the European funded project EmPower, which concentrates on power electronic applications.

Here, three different power levels are of interest:50W single die packages with fast rectifier diodes500W power modules for electric bicycle application50kW power modules for HEV and EV application

All three application fields are based on a similar concept. The so called power core provides the base for the package/module. This power core contains the embedded semiconductor(s) and is manufactured using printed circuit board processing on a large panel format of 18 by 24 inches. Electrical contacts to the embedded dies are made by laser drilled micro vias and copper filling. A major advantage of such a direct copper contact, compared to the conventionally used wire bond, is its high reliability and the improved electrical performance. By the reduction of the inductance of these interconnects, switching losses can be reduced significantly, allowing an improved and faster switching.

For the higher power modules additionally thermal management is required. Here a construction of IMS substrates and the power core is chosen. This construction enables a double sided cooling and also the electrical isolation of the module to the cooler. The connection between power core and IMS substrates is made by low temperature and low pressure Ag sintering.

All three applications fields will be described in detail. This will cover the development of the manufacturing process for all three power class demonstrators, as well as detailed structural analysis and reliability testing.

The development work toward highly reliable modules will be discussed in depth.

Finally the resulting demonstrators for 50W, 500W and 50kW power application and their characteristics will be presented in detail.
Electronic Chaotic Oscillator Realization with Potential Uses in Communication Systems
Authors: Rhea Benjamin K. , Werner F. T. , Harrison R. C. , Beal A. N. , Dean R. N.
Published: September 2017

Chaotic systems have some unique properties that can be taken advantage of in some practical systems. These systems have characteristics such as long-term aperiodicity, continuous power spectral density, topological mixing, and sensitivity to initial conditions, all while still having a clearly defined deterministic structure. The property of continuous power spectral density is of particular interest in spread spectrum communication applications. This work looks to maintain these complex properties in a practical custom electronic realization through careful layout and device selection. Included are simulation results demonstrating the system's sensitivity to initial conditions and topological mixing. In addition to this, the electronic simulation maintains a continuous spectral power density up the fundamental frequency of the oscillator. These simulation results are used design the chaotic oscillator in a hardware demonstration. The hardware results exhibit similar dynamics to the original motivation system. Presented here is a relatively simple electronic implementation that closely maintains the complex properties of an ideal chaotic differential equation.
Wafer Thinning for Advanced Packaging Applications
Authors: Mauer Laura , Taddei John , Kroeger Scott
Published: September 2017

Driven largely by the growing need for more data, increased functionality, and faster speeds, consumer electronic devices have sparked a revolution in IC design. As it becomes increasingly more expensive and technically challenging to scale down semiconductor devices, Moore's law is yielding to the concept of “More than Moore”, which is driving integrated functionality in smaller and thinner packages. Packaging for 2.5D and 3D has become critical to new products requiring higher performance and increased functionality in a smaller package. The use of a Through Silicon Via (TSV) has been discussed as a method for stacking die to achieve a vertical interconnect. The high costs associated with this technology have limited TSV use to a few applications such as high-bandwidth memory and logic, slowing its adoption within the industry. Lower-cost advanced packaging concepts have been developed and are now in high-volume production. Recently, alternative methods for exploiting the z-direction have turned to variations of Fan-Out Wafer Level Packaging (FOWLP), which do not include TSVs. In many of these concepts there is a need to thin the wafer to remove all of the silicon while being selective and not etching a variety of other films that include oxides, nitrides, and metals. In addition, there can be temporary bonding adhesives and mold compounds encapsulating the chips; these must remain undamaged. Another critical element of a successful process is the ability to control the profile of the silicon etch to provide uniform removal. The single wafer wet etching techniques and advanced process control developed for TSV Reveal are applicable to these structures and provide a low-cost alternative to CMP and Plasma processes. To successfully execute the process, several characteristics must be met: the silicon overburden depth and profile need to be determined, the overburden thinning etch needs a fast sculpting etchant, and the finishing etchant needs to be selective to materials that will be exposed at the completion of the etch. In addition, the tool used to perform this sequence needs to have the correct metrology capability, along with properly chosen etchants. Similarly, it is not sufficient to know the required etch profile, the software must be able to execute a unique etch profile for each wafer. In this fashion, the finishing etch time can be kept to a minimum. This is important, as many of the selective etchants have a slow etch rate, and adhesives used do not always hold up to exposure to the chemistries involved for long periods. This paper discusses the use of wet etch wafer thinning processes for new FOWLP applications.
Valorisation of vernacular farm buildings for the sustainable development of rural tourism in mountain areas of the Adriatic-Ionian macro-region
Authors: Statuto Dina , Picuno Pietro
Published: September 2017

Rural buildings play a central role on the environmental characteristics of the extra-urban land. They accompanied in the centuries the development of agricultural activities by humans, who was so able to breed cattle, to grow and yield crops, and to store, transform and process agricultural products in a functional and efficient way, working into intensive conditions, so being unaffected by the external climate. On the other hand, constructions built by the farmer-man marked the territory, influencing and steering the spontaneous development of nature, while leading to production that enabled humanity to get food. Vernacular farm buildings, often used as seasonal settlements, are in some cases organised in areas of mountain pasture for summer cattle grazing. Even if in most case they were abandoned during recent years - since people living there moved to more comfortable residences within urban settlements - their contemporary potential for preserving traditional cattle-raising procedures and dairy products, rich cultural-historical heritage and perspectives of organised tourism activities, appears a very intriguing task to be approached. Rural tourism - including agro-, eco- and cultural tourism - offers indeed new opportunities for enjoying the extra-urban land in close contact with naturally untouched landscapes. It enables to appreciate some traditional aspects that the new industrialised modern society may have forgotten. The opportunities offered by rural tourism could help in the development of environmentally friendly tourism, which is growing three times faster than those choosing mainstream trips. With the aim to valorise the vernacular rural buildings in some mountain areas of the Adriatic-Ionian macro-region, in the present paper a first approach was proposed, through the implementation of a geographical information system aimed to survey the current situation into two different mountain areas within this macro-region, located in Southern Italy and Montenegro. This first step could pave the way for future possible planning the restoration of these buildings, within the general framework of a concerted approach aimed to their safeguard and the general sustainability of their landscape inclusion, fighting the progressive abandonment of rural land. The exploitation of their unexpressed potential in the sector of tourism usage, together with cultural and historical heritage, rich tradition and old infrastructure, would therefore reveal an interesting profitable way for their valorisation.
Multi-component Lattice Boltzmann simulation of the hydrodynamics in drip emitters
Authors: Falcucci Giacomo , Krastev Vesselin K. , Biscarini Chiara
Published: September 2017

In this paper, we propose a fast and efficient numerical technique based on the Lattice Boltzmann method (LBM) to model the flow through a reference drip emitter geometry. The aim of the study is to demonstrate the applicability of the LBM as a reliable simulation tool for the hydraulic optimisation of irrigation systems. Results for the water flow through a rectangular drip emitter are in good agreement with literature numerical and experimental data. Furthermore, we demonstrate the feasibility of the proposed model to simulate a multi-component flow that could be used to simulate the presence of additives, contaminants, and suspended particles.
Testing mechanical characteristics of chestnut stakes used in bed sills for stream restoration
Authors: Benfratello Salvatore , Di Stefano Costanza , Ferro Vito , Palizzolo Luigi
Published: September 2017

Using of wood elements for constructing bed sills in Mediterranean streams, where the banks are not protected by tree vegetation, needs an evaluation of biological and mechanical characteristics for evaluating both the wood durability and the effectiveness of the stream restoration project. Very few studies have dealt both with the decay of mechanical characteristics of wood elements employed for stream restoration works and with the changes over time of physical and chemical wood characters. In this paper, for a wood and stone bed sill located in a stream having no shaded banks, the changes of physical and chemical characters detected after 12, 18, 24, 30, 36, 42 and 48 months on chestnut stakes are preliminarily recalled. Then, using three chestnut stakes extracted after 96 and 108 months and two unaltered stakes, as reference condition, the mechanical compression tests were carried out. The results of the compression tests for both runs (altered and unaltered stake) allowed to establish the influence of the ageing process on the compressive strength and stiffness of the chestnut wood. Finally, using two chestnut stake extracted after 108 and 120 months and two unaltered stakes, the flexural tests were carried out by a four points scheme (two supporting points and two loading points) according to UNI EN 408-2012 standard. The results of the flexural tests for both runs (altered and unaltered stake) allowed to establish that the wood ageing process determines the decay of mechanical strength of the material and reduces the bending strength of the chestnut wood. From an applicative point of view, the obtained results showed that after 10 years the mechanical resistance characteristics of the wood stakes are less than those corresponding to the undisturbed reference condition.
Thermal comfort optimisation of vernacular rural buildings: passive solutions to retrofit a typical farmhouse in central Italy
Authors: Menconi Maria Elena , Chiappini Massimo , Hensen Jan L.M. , Grohmann David
Published: September 2017

An adequate retrofitting of traditional rural buildings requires to preserve their formal characteristics and to understand the constructive elements that compose them and which are different in different geographical areas. This paper analyses the typical farmhouses in central Italy. Starting from the definition of a vernacular building model, the paper analyses its performance in terms of thermal comfort and energy efficiency. The methodology involves the use of energy dynamic simulations coupled with optimisation techniques aimed to identify the best combinations of insulating materials in terms of choice of material and its optimal location in the envelope. The paper demonstrates the good thermal and energy performance of farmhouses in central Italy. The results of the optimisation process showed that in these buildings, with the addition of insulation materials with low conductivity the perceived discomfort in the inhabited areas of the building can be reduced by 79% and the energy consumption related to heating can be reduced by 77%. The level of insulation of the pavement that separates the ground and first floor needs to be more moderate to promote the heat flow between floors during summer. The sensitivity analysis shows that the most influential component for thermal comfort is the roof insulation.
Mitigating heat stress of dairy cows bred in a free-stall barn by sprinkler systems coupled with forced ventilation
Authors: D'Emilio Alessandro , Porto Simona M.C. , Cascone Giovanni , Bella Marco , Gulino Marco
Published: September 2017

This paper presents the results of a research study which had the objective of investigating the effect of a sprinkler system coupled with forced ventilation on the heat stress of dairy cows bred in a free stall barn without paddock. To this aim, an experiment was carried out inside a free-stall dairy house equipped with two different cooling systems: a fogging system associated with forced ventilation in the resting area and a sprinkler system associated with forced ventilation in the feeding alley. The experiment regarded two adjacent pens of the barn and was constituted by three different trials carried out in the following periods: 27th June – 7th July (P1), 25th July – 4th August (P2), 24th August – 3rd September (P3). The experimental protocol of each trial required that the treatment group was housed in one pen where the two cooling systems were always activated following an established timetable, whereas the control group was housed in the other pen, where the sprinkler system associated with forced ventilation was always deactivated. Climatic parameters were measured inside each pen of the barn and outside. Then, thermal humidity index (THI) was calculated. Rectal temperature and respiration rate of a sample of dairy cows were monitored each day during the three periods considered (P1, P2 and P3). During the three trials the cows of both groups were subjected to climatic conditions that resulted in average daily THI values between 72.8 and 74.7, corresponding to mild or moderate heat stress. However, during daytime, air temperature and relative humidity reached values corresponding to a severe heat stress, as attested by the maximum THI values that were higher than or very close to 80. Furthermore, it was observed that the sprinklers do not influence the microclimatic conditions. However, the physiological parameters values of the treatment group were always significantly lower than the corresponding ones of the control group. Specifically, the system especially influenced the respiration rate that, in the treatment group, was close to 50 breath/min, while in the control group it reached 70 breath/min. The sprinkler system had more limited effects on rectal temperature that, however, in the treatment group was significantly lower than in the control group (38.7°C to 38.8°C vs 39.1°C 39.4°C) in all the three periods of the experiment. These results show that the sprinkler system could be useful to mitigate heat stress in dairy cows.
A Short Proof of the Characterization of Model Sets by Almost Automorphy
Authors: Aujogue Jean-Baptiste
Published: September 2017

The aim of this note is to provide a conceptually simple demonstration of the fact that repetitive model sets are characterized as the repetitive Meyer sets with an almost automorphic associated dynamical system.
Xenophobic activities and its impact on African peace and development
Authors: Wilson Goddey
Published: September 2017

Africa is noted for peaceful coexistence and cooperation among member states in the pursuit of development of both the citizens and the continent. However, in recent time, African peace and development is threatened by xenophobic activities, thereby giving Africa a negative image in the international system. This prompts our study, which is aimed at identifying the causes of xenophobic activities in Africa, and examining its impacts on African peace and development. Documentary sources were used to generate data for the study and content analysis used to interpret the data. Bio-cultural theory is the framework used to give theoretical explanations to xenophobic activities in Africa. The study’s findings indicated that there are issues of xenophobic activities in different African States at different times, and such activities have significant impact on African peace and development. The study made advances on the modalities to manage xenophobic activities in Africa.Keywords: Violence, activities, development, peace, xenophobia
Biostratigraphic evidence of early cretaceous (Aptian – Albian) in Cote D'ivoire Sedimenatry Basin based on planktic foraminiferal data
Authors: Bamba K.M. , Digbehi B.Z. , Goua E.T. , Baikoro B , Doukoure M
Published: September 2017

Aptian – Albian planktonic foraminifera were studied from seven boreholes MK 1, MK 2, MK 3, MK 4, MK 5, MK 6 and MK 7 drilled in Cote d’Ivoire sedimentary basin. The latest Aptian was identified in holes by very small size planktonic assemblages represented by Hedbergella maslakovae, Hedbergella similis Globigerinelloides duboisi and Globigerinelloides clavatus. Albian planktonic assemblage was characterized by Ticinella primula, Ticinella roberti, Ticinella raynaudi, Ticinella madecassiana, Biticinella breggiensis, Hedbergella rischi, Hedbergella gorbachikae, Hedbergella angolae, Costellagerina lybica, Praeglobotruncana delrioensis. The presence of latest Aptian planktonic assemblages suggest that marine conditions were already established during Late Aptian - Early Albian within Côte d'Ivoire sedimentary basin during this period.Keywords: Aptian, Albian, Cote d’Ivoire, Planktonic, Foraminifera
Suitability of large scale Jatropha curcus cultivation in Edo State: a preliminary assessment using the Analytical Hierarchy Process (AHP) method
Authors: Emeribe C.N. , Uwadia N.O. , Umoru G.L. , Efegoma R.O.
Published: September 2017

The aim of this study is to assess the suitability of agro-ecological regions for Jatropha Curcas cultivation using GIS and Analytical Hierarchy Process (AHP) tools. Rainfall amount and temperature data were collected from the Nigerian Meteorological Agency (NIMET), Federal Ministry of Aviation, Oshodi, Lagos and Climate Prediction Centre of the United States Agency for International Development (USAID) for a period of 3 years (2010 - 2012). Rainfall amounts in Edo state ranges between 1400mm-1500mm in the south most part of the state and decreases to 1200mm-1350mm at the centre of the State and 1000mm-1200mm in the north. These values fall within the optimal range for Jatropha cultivation. There are six (6) to seven (7) months of moisture adequacy in Edo state usually from April/May – September/October. Within this period, there is adequate moisture supply to satisfy the consumptive needs of Jatrophacultivation during its vegetative and flowering/fruiting stages. There are two rainfall peaks in Edo state namely May/June and September/October which guarantees two-times planting seasons, namely April planting season prior to the first rainfall peak in May/June and July/August planting season before the last rainfall peak (September/October). Runoff peaks in Edo state occur between September and October. Within this period soils are at field capacity and not suitable for onset of Jatropha cultivation. Analysis of slope conditions in Edo state showed that vast expanse of land in the state may be categorized as highly suitable with small patches of moderately suitable locations in the north. Soil condition in Edo state showed marginally suitable for soils in the mangrove region, southernmost part of the state and moderately suitable for hydromorphic soils of the Owena Basin west of the State. Finally, the result of multi-criteria analysis showed that Edo state can be grouped into two main classes of suitability namely; moderately and highly.Keywords: Jatropha Curcas, Energy production, Climatic factors, moisture storage, Soil condition
Energy efficiency and sustainability: evaluation of electricity consumer’s behaviour towards electricity usage and energy conservation
Authors: Udoakah Y.N. , Okure I.G.
Published: September 2017

Energy sustainability, conservation and use have become a more predominant trend globally. In view of the important nature of the energy sectors and the effect it has on national development of any country, there is a growing concern about energy consumption and waste, particularly about electricity consumer’s attitudes, behaviour and practices with respect to energy sustainability. Employing the context of cognitive, affective and behavioural components (ABC/Tricomponent Model of Attitude), this work presents the results of a systematic survey and analysis of electricity consumer’s attitudes, behaviours and practices towards energy use and sustainability. Using the random sampling method, the perception questionnaires were administered to respondents across the various streets chosen. The results indicate that although there is some level of awareness with regards to the need for energy sustainability and efficient practices, most consumers did not engage in such practices even among the highly educated. Taking consumer’s knowledge and use of energy saving devices as a case in point, of the 990 respondents, 78% affirmed to having this knowledge while 11% asserted to not knowing, with another 11% having no knowledge of either energy saving devices or its ability to conserve energy. Furthermore, of the 78 % respondents who asserted to being in the know, only 50.8 % actually used such devices while the remaining 49.2% did not despite being fully aware. Significant also is the fact that for respondents who did not have knowledge of electrical energy conservation, 71% indicated their willingness to learn more about the issue. The study therefore recommended that it is necessary to promote efficient use of electricity in order to benefit various stakeholders and it also submitted that there are energy-related attitudes and energy-saving behaviour that could be practiced and performed at little or no cost.Keywords: Energy efficiency, Energy conservation, Electricity usage, Consumer’s behaviour, Sustainability, Energy saving devices
Creativity of secondary school students: entrepreneurial skills acquisition in the construction of potentiometer in physics
Authors: Avwiri Eseroghene
Published: September 2017

The study adopted a quasi-experimental design using a pre-test, post-test control design in order to investigate the entrepreneurial skills and creative abilities of secondary school students in Physics. The study was carried out in Obio/Akpo Local Government Area of Rivers State of Nigeria, using purposive sampling technique. Sixty (60) SS2 Physics students were drawn from a population of six hundred (600) students. The instruments for the study are Creative Ability Test (CAT) and Entrepreneurial Skill Acquisition Test (ESAT). The ESAT was use for an on the spot assessment. The reliability coefficients of the instruments are 0.95 for CAT and 0.74 for ESAT, using Kuder- Richardson Formula (K-R-21) and Cronbach Alpha respectively. The students in different groups were taught using three teaching strategies namely Demonstration, Guided-Inquiry and Cooperative strategies on the entrepreneurial skills in construction of potentiometer. The students were assessed before and after treatment on acquisition and use of entrepreneurial skills (measurement, manipulative and finger dexterity skills) in the making of potentiometer. Three research questions and hypotheses guided the study. Data collated were analysed using mean and percentage to answer the research questions while Analysis of Co-variance (ANCOVA) was used to test the null hypotheses. Result shows that there is no significant difference in the interaction of the teaching strategies on the students of high, average and low creative abilities in their acquisition of entrepreneurial skills in the construction of potentiometer. However, the main effect of the teaching strategy is significant. Based on these findings it was recommended that Demonstration, Guided-inquiry and Cooperative innovative teaching strategies be used in instruction in Entrepreneurial skill acquisition such as the construction of potentiometer, in physics.Keywords: Guided-Discovery, Creative Abilities, Instructional Strategies, Entrepreneurship and Skills Acquisition
Long-term O3–precursor relationships in Hong Kong: field observation and model simulation
Authors: Wang Yu , Wang Hao , Guo Hai , Lyu Xiaopu , Cheng Hairong , Ling Zhenhao , Louie Peter K. K. , Simpson Isobel J. , Meinardi Simone , Blake Donald R.
Published: September 2017

Abstract. Over the past 10 years (2005–2014), ground-level O3 in Hong Kong has consistently increased in all seasons except winter, despite the yearly reduction of its precursors, i.e. nitrogen oxides (NOx =  NO + NO2), total volatile organic compounds (TVOCs), and carbon monoxide (CO). To explain the contradictory phenomena, an observation-based box model (OBM) coupled with CB05 mechanism was applied in order to understand the influence of both locally produced O3 and regional transport. The simulation of locally produced O3 showed an increasing trend in spring, a decreasing trend in autumn, and no changes in summer and winter. The O3 increase in spring was caused by the net effect of more rapid decrease in NO titration and unchanged TVOC reactivity despite decreased TVOC mixing ratios, while the decreased local O3 formation in autumn was mainly due to the reduction of aromatic VOC mixing ratios and the TVOC reactivity and much slower decrease in NO titration. However, the decreased in situ O3 formation in autumn was overridden by the regional contribution, resulting in elevated O3 observations. Furthermore, the OBM-derived relative incremental reactivity indicated that the O3 formation was VOC-limited in all seasons, and that the long-term O3 formation was more sensitive to VOCs and less to NOx and CO in the past 10 years. In addition, the OBM results found that the contributions of aromatics to O3 formation decreased in all seasons of these years, particularly in autumn, probably due to the effective control of solvent-related sources. In contrast, the contributions of alkenes increased, suggesting a continuing need to reduce traffic emissions. The findings provide updated information on photochemical pollution and its impact in Hong Kong.
Two-stream instabilities from the lower-hybrid frequency to the electron cyclotron frequency: application to the front of quasi-perpendicular shocks
Authors: Muschietti Laurent , Lembège Bertrand
Published: September 2017

Abstract. Quasi-perpendicular supercritical shocks are characterized by the presence of a magnetic foot due to the accumulation of a fraction of the incoming ions that is reflected by the shock front. There, three different plasma populations coexist (incoming ion core, reflected ion beam, electrons) and can excite various two-stream instabilities (TSIs) owing to their relative drifts. These instabilities represent local sources of turbulence with a wide frequency range extending from the lower hybrid to the electron cyclotron. Their linear features are analyzed by means of both a dispersion study and numerical PIC simulations. Three main types of TSI and correspondingly excited waves are identified: i. Oblique whistlers due to the (so-called fast) relative drift between reflected ions/electrons; the waves propagate toward upstream away from the shock front at a strongly oblique angle (θ ∼ 50°) to the ambient magnetic field Bo, have frequencies a few times the lower hybrid, and have wavelengths a fraction of the ion inertia length c∕ωpi. ii. Quasi-perpendicular whistlers due to the (so-called slow) relative drift between incoming ions/electrons; the waves propagate toward the shock ramp at an angle θ a few degrees off 90°, have frequencies around the lower hybrid, and have wavelengths several times the electron inertia length c∕ωpe. iii. Extended Bernstein waves which also propagate in the quasi-perpendicular domain, yet are due to the (so-called fast) relative drift between reflected ions/electrons; the instability is an extension of the electron cyclotron drift instability (normally strictly perpendicular and electrostatic) and produces waves with a magnetic component which have frequencies close to the electron cyclotron as well as wavelengths close to the electron gyroradius and which propagate toward upstream. Present results are compared with previous works in order to stress some features not previously analyzed and to define a more synthetic view of these TSIs.
Precipitation–fire linkages in Indonesia (1997–2015)
Authors: Fanin Thierry , van der Werf Guido R.
Published: September 2017

Abstract. Over the past decades, fires have burned annually in Indonesia, yet the strength of the fire season is for a large part modulated by the El Niño Southern Oscillation (ENSO). The two most recent very strong El Niño years were 2015 and 1997. Both years involved high incidences of fire in Indonesia. At present, there is no consistent satellite data stream spanning the full 19-year record, thereby complicating a comparison between these two fire seasons. We have investigated how various fire and precipitation datasets can be merged to better compare the fire dynamics in 1997 and 2015 as well as in intermediary years. We combined nighttime active fire detections from the Along Track Scanning Radiometer (ATSR) World Fire Atlas (WFA) available from 1997 until 2012 and the nighttime subset of the Moderate-Resolution Imaging Spectroradiometer (MODIS) sensor from 2001 until now. For the overlapping period, MODIS detected about 4 times more fires than ATSR, but this ratio varied spatially. Although the reasons behind this spatial variability remain unclear, the coefficient of determination for the overlapping period was high (R2 = 0. 97, based on monthly data) and allowed for a consistent time series. We then constructed a rainfall time series based on the Global Precipitation Climatology Project (GPCP, 1997–2015) and the Tropical Rainfall Measurement Mission Project (TRMM, 1998–2015). Relations between antecedent rainfall and fire activity were not uniform in Indonesia. In southern Sumatra and Kalimantan, we found that 120 days of rainfall accumulation had the highest coefficient of determination with annual fire intensity. In northern Sumatra, this period was only 30 days. Thresholds of 200 and 305 mm average rainfall accumulation before each active fire were identified to generate a high-incidence fire year in southern Sumatra and southern Kalimantan, respectively. The number of active fires detected in 1997 was 2.2 times higher than in 2015. Assuming the ratio between nighttime and total active fires did not change, the 1997 season was thus about twice as severe as the one in 2015. Although large, the difference is smaller than found in fire emission estimates from the Global Fire Emissions Database (GFED). Besides different rainfall amounts and patterns, the two-fold difference between 1997 and 2015 may be attributed to a weaker El Niño and neutral Indian Ocean Dipole (IOD) conditions in the later year. The fraction of fires burning in peatlands was higher in 2015 compared to 1997 (61 and 45 %, respectively). Finally, we found that the non-linearity between rainfall and fire in Indonesia stems from longer periods without rain in extremely dry years.
Source, composition, and environmental implication of neutral carbohydrates in sediment cores of subtropical reservoirs, South China
Authors: Duan Dandan , Zhang Dainan , Yang Yu , Wang Jingfu , Chen Jing'an , Ran Yong
Published: September 2017

Abstract. Neutral monosaccharides, algal organic matter (AOM), and carbon stable isotope ratios in three sediment cores of various trophic reservoirs in South China were determined by high-performance anion-exchange chromatography, Rock-Eval pyrolysis, and Finnigan Delta Plus XL mass spectrometry, respectively. The carbon isotopic compositions were corrected for the Suess effect. The concentrations of total neutral carbohydrates (TCHO) range from 0.51 to 6.4 mg g−1 at mesotrophic reservoirs, and from 0.83 to 2.56 mg g−1 at an oligotrophic reservoir. Monosaccharide compositions and diagnostic parameters indicate a predominant contribution of phytoplankton in each of the three cores, which is consistent with the results inferred from the corrected carbon isotopic data and C∕N ratios. The sedimentary neutral carbohydrates are likely to be structural polysaccharides and/or preserved in sediment minerals, which are resistant to degradation in the sediments. Moreover, the monosaccharide contents are highly related to the carbon isotopic data, algal productivity estimated from the hydrogen index, and increasing mean air temperature during the past 60 years. The nutrient input, however, is not a key factor affecting the primary productivity in the three reservoirs. The above evidence demonstrates that some of the resistant monosaccharides have been significantly elevated by climate change, even in low-latitude regions.
Modelling past, present and future peatland carbon accumulation across the pan-Arctic region
Authors: Chaudhary Nitin , Miller Paul A. , Smith Benjamin
Published: September 2017

Abstract. Most northern peatlands developed during the Holocene, sequestering large amounts of carbon in terrestrial ecosystems. However, recent syntheses have highlighted the gaps in our understanding of peatland carbon accumulation. Assessments of the long-term carbon accumulation rate and possible warming-driven changes in these accumulation rates can therefore benefit from process-based modelling studies. We employed an individual-based dynamic global ecosystem model with dynamic peatland and permafrost functionalities and patch-based vegetation dynamics to quantify long-term carbon accumulation rates and to assess the effects of historical and projected climate change on peatland carbon balances across the pan-Arctic region. Our results are broadly consistent with published regional and global carbon accumulation estimates. A majority of modelled peatland sites in Scandinavia, Europe, Russia and central and eastern Canada change from carbon sinks through the Holocene to potential carbon sources in the coming century. In contrast, the carbon sink capacity of modelled sites in Siberia, far eastern Russia, Alaska and western and northern Canada was predicted to increase in the coming century. The greatest changes were evident in eastern Siberia, north-western Canada and in Alaska, where peat production hampered by permafrost and low productivity due the cold climate in these regions in the past was simulated to increase greatly due to warming, a wetter climate and higher CO2 levels by the year 2100. In contrast, our model predicts that sites that are expected to experience reduced precipitation rates and are currently permafrost free will lose more carbon in the future.