bluuebunny/crossref_metadata_2025 huggingface dataset:
The influence of gamma irradiation doses on the morphological and physical properties of wheat
Authors: El-Kameesy S U , Salama E , Ghannam M M , Roshdy S
Published: August 2019

The fluorescence and light absorption and dielectric characteristics of wheat are studied to investigate the influence of gamma exposure on germination, morphological and physical properties of wheat plant. Wheat grains were irradiated at 0, 1.5, 2, 2.5, 3, 5, 7 and 10 krad. The obtained results indicated that, pronounced increase in germination rate, plant height, and root length were obtained at 2.5 krad treatment. Furthermore, those characteristics were evaluated for chlorophyll at different doses given to wheat grains. The analysis of these spectra indicates that the maximum emission and absorption obtained at 2.5 krad gamma irradiation dose. Moreover, the dielectric properties and the electric conductivity of the different irradiated samples were determined in the frequency range 20 Hz- 100 kHz. The obtained data were treated precisely to determine the dielectric constant and the Ac conductivity that easily describe the plant growth. The predictions of the obtained results give further support for the 2.5 krad to be the best dose to stimulate the plant growth features.
Analysis of a rotary passive heat recovery device for natural ventilation windcatcher
Authors: Connor D O’ , Calautit J K , Calautit K , Shazad S , Hughes B R , Pantua C
Published: August 2019

Based on the design of traditional architecture, windcatchers are devices which provides passive ventilation by manipulating pressure differentials around buildings induced by the movement of wind and difference in temperature. In temperature climates, it is effective in providing passive cooling during summer months. However, during winter months, the low air temperature supplied to the space can cause further thermal discomfort and increase heat loss which lead to higher energy consumption. This limits the capabilities of windcatchers to provide ventilation all year round. To address this issue, the present study proposes incorporating a rotary thermal heat recovery device into the windcatcher channel and investigate its performance using numerical modelling and experimental tests. The study focused on characterizing the design and performance of the copper radial blades of the proposed heat recovery device. The predicted results of the airflow and temperature showed good agreement with the experimental tests. Two types of radial blade designs were assessed in terms of the airflow velocity and distribution, the pressure drop and the heat recovery performance.
Numerical study of a thermal storage tank enclosed PCM capsules
Authors: Lu Wei , Bi Shuqian , Wang Huakeer , Flor Jan-Frederik , Wu Yupeng , Zhang Leyi
Published: August 2019

Low-temperature thermal storage has a huge potential in residential use for regulating the energy supply. This paper proposes a new thermal storage system consisting of modular units. Users can combine different numbers of the units to achieve the desirable energy demand. In this study, a single unit was studied. The hydrated salt was used as the phase change material (PCM) and it was packed in spherical capsule. The phase change situation of each PCM balls were analysed with numerical simulation method. The results showed that the PCM balls in different position had different change rate. In the charging process, the thermal stratification happened after the middle part of the unit, the down layer PCM balls took 30% more time than upper layer to be melted completely. In discharging process, considered the user requirement, the low inlet velocity may fit the single unit. The thermal stratification also happened in the discharging process, and it is most obvious in the middle part.
Numerical model of applying PCM boards for energy saving in lightweight buildings in Shanghai
Authors: Wang Huakeer , Lu Wei , Wu Zhigen
Published: August 2019

The lightweight building industry develops fast, but it has competitively worse thermal comfort than traditional buildings because of less thermal mass. The use of phase change material (PCM) can help to solve the problem and boost the energy efficiency. In this paper, the effect of applying PCM-boards in air-conditioned lightweight buildings in Shanghai has been evaluated. A parametric study is performed considering different PCM-boards configurations, using an EnergyPlus single-zone model. The daily and annual situation have been simulated in this study, and the predictions show that the energy saving depends on the phase change temperature of PCM and seasonal temperature. The application of PCM can save up to 20.88% of energy for air conditioning system in buildings. The daily assessment reveals that the passive PCM technology inside the wall saves more energy under heating conditions than the cooling condition because of the overheating.
Holistic Optimisation of Solar-assisted Multiple Effect Evaporators (MEE)
Authors: Ramanathan Soundaram , Rakshit Dibakar
Published: August 2019

The effects of heat transfer performance of systems can be studied in combination with thermodynamic performance. The design solution of maximizing heat transfer always leads to increased entropy generation else if minimizing entropy was aimed then heat transfer got minimized. Hence there is need for holistic optimization. This paper attempts to merge the two competing criteria’s - (i) heat transfer and (ii) the thermodynamic performance of a solar assisted multiple effect evaporator system and optimize study parameters for its energy efficient operation. Solar assisted multiple effect evaporators use steam as source of energy to evaporate wastewater.

The idea of amalgamating these two factors is to observe how much reduction in the performance of one factor will improve the performance of the other. This study couples the two criteria, which has been dealt with separately, to arrive at the parameters of interest which must be fine-tuned for ensuring system performance.

Mass flow rate of steam and wastewater appeared to chiefly influence heat transfer and entropy generation of the system, negligible influence was observed on changing the concentration of the waste water or optical efficiency of the solar concentrator in single legged analysis. However through this holistic optimization study, it was found that variations in Prandtl number, i.e., the concentration of the waste water and optical efficiency of solar concentrator drastically shift the optimization balance of entropy generation and heat transfer rate.
Calibrating Perez Model Coefficients Using Subset Simulation
Authors: Meshkinkiya M , Loonen R.C.G.M. , Paolini R , Hensen J.L.M
Published: August 2019

The Perez sky diffuse model has been validated in many locations, however, studies have shown that the precision of estimation can be improved through localization of the model coefficients. This paper studies the effect of tuning Perez irradiance coefficients based on local information for estimating the incident solar radiation on tilted surfaces. The added value of a calibrated Perez model is highlighted by evaluating the heating and cooling energy needs of an office building. Calibration is performed by using Subset Simulation, i.e. a sampling technique based on Markov Chain Monte Carlo. The versatility of the Subset Simulation technique allows for handling multivariant calibration problems and is therefore suitable for finetuning Perez irradiance coefficients. Measurements of global horizontal, direct normal and diffuse horizontal solar irradiation, as well as the global solar irradiation on 90°, 30° and 15° tilted surfaces form the basis of the calibration. It is found that in the studied location, the default Perez model overestimates the incident solar radiation on vertical surfaces facing south. The calibrated coefficients are then embedded in the source code of EnergyPlus. Simulations with a reference office show that the effect of calibrating Perez coefficients can be significant, because it leads to approximately 12% difference in predicted annual cooling energy use and 9% difference in peak cooling loads, respectively.
A climate zone approach to global solar radiation modelling using artificial neural networks
Authors: Yang Liu , Huo Xujie , W Li Danny H , Lam Joseph C
Published: August 2019

Information on solar availability is crucial in the study of both passive building designs and active solar energy systems. There are still many locations within different climate zones worldwide that do not have solar radiation measurements. Correlation between solar radiation and the more commonly measured meteorological variables such as temperature and sunshine hours is useful for locations with no measured solar radiation data. This is also useful for locations with measured solar radiation data, in that any missing data due to equipment breakdown or malfunction can be modelled. Global solar radiation (GSR) was modelled for 96 cities in different climate zones across China using artificial neural networks (ANNs). The novelty of this study is the climate zone approach, by which locations with similar climates were modelled together. Climate classification was based on both the traditional thermal climates and the solar climates. Two sets of models were developed based on measured diurnal temperatures and sunshine hours. Model performance in terms of the predictive power of ANN solar radiation models was evaluated through the Nash-Sutcliffe efficiency coefficient (NSEC). Error analysis of the predicted solar radiation as compared with the measured data was also conducted for each of the 96 cities.
Synthesis of a carbazole-substituted diphenylethylene hole transporting material and application in perovskite solar cells
Authors: Li Juncong , Zhu Hongwei , Li Xianggao , Wang Shirong , Xiao Yin
Published: August 2019

In this work, a carbazole-substituted stilbene derivatives hole transporting material, 9,9’-(ethene-1,1-diylbis(4,1-phenylene))bis(3,6-dimethoxy-9H-carbazole) (EPC) was designed and synthesized. The structure was characterized by FT-IR spectroscopy, 1H NMR, 13C NMR and MS. The glass transition temperature is 95.09°C and the 5% weight loss temperature is 423.37°C by DSC/TG analysis. Through the UV-Vis absorption spectrum combined with cyclic voltammetry, the energy level of the highest occupied molecular orbital (HOMO) of EPC and the lowest unoccupied orbital (LUMO) energy level were obtained (-5.38 eV, -2.19 eV). The energy level is well matched with methylamine lead iodine crystals. A mesoporous structure perovskite solar cell was fabricated based on the undoped EPC, and photoelectric conversion efficiency of 13.11% was obtained. After 600 hours of storage in a dark environment at 25°C and 60% relative humidity, 82% of the initial efficiency was obtained. This work provides new ideas for the development of undoped hole transporting materials.
Design of a small size PTC: computational model for the receiver tube and validation with heat loss test
Authors: Salvestroni M , Pierucci G , Fagioli F , Pourreza A , Messeri M , Taddei F , Hosouli S , Rashidi H , Lucia M De
Published: August 2019

In EU, the residential sector is responsible for the 40% of the total energy consumption. The integration of solar technologies in buildings is therefore necessary in order to reduce the use of fossil fuels. Concentrating collectors could offer an interesting solution but nowadays their application in buildings is rare due to high costs, large dimensions and complexity of the system. A novel small parabolic trough collector (PTC) has been conceived to overcome these limits and to allow the integration in buildings. The main features of realized prototype are the compact dimensions, strongly reduced compared to the PTC standards, and modularity. The paper deals with the numerical analysis necessary to design the concentrating collector properly and its validation with experimental results. An optical analysis has allowed to select the optimum values for the parameters of the parabola, aperture and rim angle. A thermo-fluid dynamics finite element model has been developed with Comsol Multiphysics, to analyse the relevant physical characteristics and to predict the performance of the receiver tube. The efficiency curve of the collector has been extracted. Successively a receiver tube has been built based on the indications of FEM model for what concerns geometry and materials. In order to evaluate the heat loss of the receiver and to validate the finite element model, a test bench has been realized. The results of off-sun heat loss tests on the receiver tube are reported for several temperatures. The computational model is in good agreement with experimental results and therefore it is validated.
Study on aluminum honeycomb plate solar air collector and its building heating potential in western Sichuan
Authors: Meng T , Meng X , Zhao Y , Jing C
Published: August 2019

In this paper, the efficiency of aluminum honeycomb plate solar air collector has been analyzed through both experimental and theoretical methods, followed by a study a on the applicability of using honeycomb plate solar air collector in western Sichuan. Solar energy on building vertical wall has been investigated firstly, then the solar heating potential of building facades in three representative regions of western Sichuan has been computed. Lumped parameter method was used to simulate dynamic heating capacity of the collector. The results indicated that aluminum honeycomb plate solar air collector has a relatively large heating potential in western Sichuan.
Graphene oxide stabilized carbon nanotube-water nanofluids for direct absorption solar collectors
Authors: Wang Xinzhi , Liu Dan , Liu Xing , He Yurong
Published: August 2019

The utilization of solar thermal energy has shown remarkable growth recently. Due to the development of nanomaterials, suspensions of nanoparticles (nanofluids) have exhibited great performance in the solar thermal systems, especially in direct absorption solar collectors (DASC). The fundamental advantage of DASC by using nanofluids is the minimizing of solar energy transfer steps and reducing thermal losses in converting sunlight, as nanoparticles could harvest the solar energy directly and achieve good photothermal conversion properties. Carbon nanotube (CNT) based nanofluids showed great potential as a working fluid in DASC. Nevertheless, the stability of CNTs in suspensions is the main obstacle for the large use of CNT nanofluids. In this work, small amount of graphene oxide (GO) was introduced to stabilize CNT-water nanofluids without using any other organic surfactants. The GO stabilized CNT nanofluids exhibited long-term and high-temperature stability. The π-π interactions between the GO and CNT played a significant role for the good dispersion and stability of CNT in water. Furthermore, optical characterizations showed that the GO stabilized CNT nanofluids have widely absorbing over the solar spectrum which enabled highly efficient solar energy collections. Eventually, photothermal conversion performance of GO stabilized CNT nanofluids was tested under an irradiation of simulated solar light and the nanofluid demonstrated a high efficiency in DASC. The long-term stability coupled with broadband absorption properties of GO stabilized CNT nanofluids make them ideal candidates as photothermal conversion media for direct solar thermal collectors.
Optimization Investigation on Wavy Channel Printed Circuit Heat Exchanger for Solar Energy Powered Brayton Cycle
Authors: Li Y Z , Xie Y H , Zhang D
Published: August 2019

The Printed Circuit Heat Exchanger(PCHE) has received widely attention for their high effectiveness and compact size and they appear promising to be employed as the heat exchanger in solar thermal system. In this research, the thermal and hydraulic performance of the wavy channels for solar energy were investigated detailed in different amplitudes, inclined angles and channel diameters. The three-dimensional numerical analysis was performed by computational fluid dynamics(CFD) tool and the model is validated by comparing with previous experimental data. Besides, it was difficult to get the universal correlations of Nusselt number and friction factor for various geometrical parameters. In this article, the Kriging response surface method is applied to predict the friction factor and j factor for PCHE wavy channels in different geometrical parameters based on the CFD simulation results. The thermal-hydraulic characters predicted by Kriging response surface showed overall good agreement with the CFD results. Moreover, one of the most popular multi-objective genetic algorithms NSGA-II was adopted in optimization. to maximize j factor, while minimize the fanning friction factor.
The Assembly of Embedded Systems for Integrated Photovoltaic windows in Rural Buildings (E-IPB)
Authors: Shanks K , Baig Hasan , Knowles Ashley , Brierley Adam , Orr Henry , Patel Jayesh , Foster Neil , Ball Stephen , Sun Yanyi , Wu Yupeng , Senthilarasu Sundaram , Mallick Tapas
Published: August 2019

Embedded PV systems are required to help improve the synergy of renewable energy and smart buildings. A novel concentrator photovoltaic (CPV) system embedded as a window for integration into buildings is presented. The system is made up of crossed compound parabolic concentrators (CCPC), Talesun Silicon solar cells and glass panes. The materials and manufacturing methods are presented along with their advantages and disidvantages. Two sized prototypes are presented, 7cm by 7cm and 20cm by 20cm. The maximum power obtained was 3.53 Watts for the larger prototype. The glass CCPC optics produce more power but plastic alternatives are only 44% the weight of the glass optics. The best performing plastic optics were made of Topaz and injection moulded. The cell soldering and alignment method is explored and in particular silver tracks printed on glass are analysed for their resistance, aesthetics and benefit to the assembly process. Using plastic optics for CPV technology is a relatively new area of research, and the combination of silver tracks printed on glass could make this innovative design revolutionary in its field.
Estimating hourly global solar irradiance using artificial neural networks – A case study of Hong Kong
Authors: Chen Wenqiang , W. Li Danny H. , Li Shuyang , Lam Joseph C
Published: August 2019

Solar energy is the most popular resource for power generation among the various available renewable energy alternatives. Solar radiation data are important for solar photovoltaic (PV) systems and passive energy-efficient building designs. Due to the unavailability of measurement in rural locations, solar radiation prediction models are required. In recent years, the Artificial Neural Networks (ANN) were successfully used for predicting solar radiation. However, previous works indicated that the ANN techniques were mainly focusing on prediction of monthly average or daily solar radiation, a few of them were modelled for predicting solar irradiance in hourly basis. In this study, prediction models of global solar irradiance on a horizontal surface will be developed based on neural-network techniques. Hourly meteorological variables between 2012 and 2015 acquired from the measurements made by local meteorological station were used for the study. To consider the effectiveness of individual predictors, different combinations of input variables were analysed using the Levenberg-Marquardt (LM) algorithm. Finally, equations were modelled by regression based on the important predictors. The developed models were used to estimate the global irradiance and assessed against measurement results.
Experimental and theoretical research on bending behaviour of photovoltaic panels with a special boundary condition
Authors: Zhang T Y , Xie L Z , Li Y X , Mallick T K , Wei Q Z , Hao X , He B
Published: August 2019

Currently, the photovoltaic panels widely manufactured on market are composed of stiff front and back layers and the solar cells embedded in a soft polymeric interlayer. The wind and snow pressure are the usual loads to which working photovoltaic panels need to face, and it needs the panels keep undamaged under those pressure when they generate electricity. Therefore, an accurate and systematic research on bending behaviour of photovoltaic panels is important and necessary. In this paper classical lamination theory (CLT) considering soft interlayer is applied to build governing equations of the panel. A Rayleigh-Rita method is modified to solve the governing equations and calculate the static deformation and inter force of the photovoltaic panel. Different from many previous researches only analysing simply supported boundary condition for four edges, a special boundary condition which consists of two opposite edges simply supported and the others two free is studied in this paper. A closed form solution is derived out and used to do the numerical calculation. The corresponding bending experiments of photovoltaic panels are completed. Comparing the numerical results with experiment results, the accuracy of the analytical solutions are verified. The influence of boundary condition is shown by comparing the results with previous researches, and a guide for the photovoltaic panel installation is finally proposed based on those conclusions.
A novel Fluid-Structure Interaction modelling and optimisation of roofing designs of buildings for typhoon resilience
Authors: Jay Pantua Conrad Allan , Calautit John Kaiser , Wu Yupeng
Published: August 2019

Stronger typhoons have been more frequent in the Western Pacific region. Typhoon Haiyan caused widespread loss of life and destruction to properties when in made landfall in the Philippines in 2013. An estimated 1.1 million homes were damaged or destroyed in the aftermath. Damage surveys show extensive roofing damage evident in most detached structures attributed to strong winds. Clearly, there is a need to evaluate the current roofing designs and its structural integrity for it to properly respond to extreme environmental events in the future. Using a novel Fluid Structure Interaction (FSI) approach, this study evaluated a single detached gabled building made of timber which is common in the Philippines. The building was subjected to typhoon strength winds in an urban environment using Computational Fluid Dynamics (CFD) analysis. Atmospheric Boundary Layer (ABL) flow simulation was conducted to predict the pressure distribution around the structure. A structural model of the roofing support was then developed, and the structural analysis performed using FSI to predict failure in the sheathing and the supports. The results of the study show the structural weaknesses in the current design considering the wind angle, structural frame and materials.
A method for a cradle-to-cradle life cycle assessment of integrated collector-storage solar water heaters
Authors: Saint Ruth M , Pomponi Francesco , Currie John I
Published: August 2019

Solar thermal technologies are a potentially free and limitless source of energy. Due to the high demand for domestic hot water and the longer insolation periods during summer in Scotland, solar water heating (SWH) systems are a promising renewable energy technology. One of the systems within this technology is the integrated collector-storage solar water heater (ICSSWH). Existing research has predominantly focussed on the technical and economic aspects, with aims to reduce costs whilst maintaining operational performance. This begs the question, what are the true environmental costs of ICSSWH systems? Life cycle assessment (LCA) is an established methodology to evaluate the environmental performance of a product or a system across its life cycle. The aim of this paper is therefore to present an ICSSWH system from an LCA standpoint, also considering the current shift towards a more circular economy. Preliminary field data from a novel ICSSWH designed at Edinburgh Napier University will be presented. The paper will detail the data sources, impact assessment methods and software tools that will be used. Key outcomes from this research show that a holistic ICSSWH design, which considers whole-life implications, does not compromise efficiency and economic viability.
Some important properties of strandboard manufactured from andong bamboo (Gigantochloa pseudoarundinacea)
Authors: Sulastiningsih I M , Indrawan D A , Trisatya D R
Published: August 2019

Andong bamboo (Gigantochloa pseudoarundinacea) is one of the most important bamboo species widely planted in West Java, Indonesia, and play a prominent role in the rural economy. The bottom and the middle parts of Andong bamboo culms are suitable for laminated bamboo lumber raw material. To improve the efficiency of bamboo utilization, the upper part of Andong bamboo culms were use as raw material for strandboard production. The objective of the study was to determine the effect of strand length and specific pressure on the properties of bamboo strandboard. Laboratory scale of bamboo strandboards were fabricated using three different strand lengths (75, 100, and 150 mm), two different specific pressures applied (25 kg/cm2 and 30 kg/cm2) and glued with phenol formaldehyde with the targeted density of 0.75 g/cm3. Some physical and mechanical properties of bamboo strandboards were determined. Results showed that the average physical properties of bamboo srandboards were 9.3% (moisture content), 0.76 g/cm3 (density), 3.1% (thickness swelling), 1.6% (wide expansion), and 25.1% (water absorpsion). The average mechanical properties of bamboo srandboards were 760.5 kgf/cm2 (MOR), 92.3 103kgf/cm2 (MOE), 5.6 kgf/cm2 (IB), and 56.5 kgf (screw holding power). Some physical and mechanical properties of bamboo strandboard were significantly affected by strand length and specific pressure.
Structural and Mechanical Properties of Carbon-Carbon Biocomposites
Authors: Tahir D , Sattar S , Fatimah S , Rauf N , Armynah B
Published: August 2019

Carbon-carbon composites (C/C composites) have been synthesized from organic sawdust as a carbon filler material and carbon asphalt as matrix of composites. The structural and mechanical properties of carbon-carbon composites from sawdust-asphalt are focused in this experiment. The structural has been characterized by using FTIR, XRD and XRF. The mechanical properties has been resulted from hardness, strength, and attrition testing. According to XRF data, CaO is the main content from carbon filler in composite decrease with increasing carbon asphalt matrix and vice versa for SO3 as the main content from carbon tar as a matrix. Changing structure of C/C composites indicated sawdust as carbon has been bound to asphalt as carbon composites. Beside this, adding carbon to carbon composites shows increasing hardness from 6,57 to 9,27 kg/mm2, strength of sample from 11,90 to 18,56 N/mm2, and decreasing attrition of material from 1,64 to 0,28 gr. According to the data shows that adding sawdust to asphalt makes increasing hardness and strength of C/C composites. It means that the C/C composites from organic material sources has a good material composites which has low degradation under high temperature, economically, and eco-friendly to apply in asphalt as material of road construction. It means that organic material very potential as a carbon-carbon composite materials for various applications.
Citric acid, an environmentally friendly adhesive and wood impregnation material-review of research
Authors: Cahyono T D , Syahidah
Published: August 2019

Citric acid’s potency to be adhesive is proven with an increasing quality of product bonding resulted from wood and other lignosellulosic materials. Wood waste, bagasse, sorghum and corn stalks, and bamboo are quality particleboard materials after addition of 20% citric acid. Moulding made of a mixture of tree bark and citric acid with the same concentration is also able to pass repeated boiling test without having any damage. Ester bond between wood’s hydroxyl group and citric acid’s hydroxyl group is formed at 180ºC and gets more optimal as the pressing temperature increases during production process. This results in an increase of board’s physical-mechanical properties pursuant to the standard. Some researches remain presenting non-standard test parameters and this is a challenge to be answered with further research. The density of Samama wood impregnated with 10% citric acid has its density increased between 17.11% and 20.13%. Samama wood does not experience a recovery of set after it has been pressed for 50 minutes at 180°C.
Characteristics of the Cement Board Using CO2 Injection Technology from Wood and Non-Wood Species
Authors: Taskirawati I , Agussalim A , Baharuddin B , Suhasman S
Published: August 2019

The fundamental weakness of the technology in manufacturing cement board is that the curing process takes a long time, which is about 28 days. CO2 injection technology has been shown to accelerate the hardening process. However, each of the wood species has a different response due to the presence of inhibitors, namely extractive component. This study aims to compare the characteristics of CO2 injection cement boards from three wood species. These three species came from hardwood, softwood, and non-wood groups, namely agathis (Agathis sp.), Gmelin (Gmelina arborea) and parring bamboo (Gigantochloa atter), respectively. The type of cement used was Portland Cement Composite (PCC). The three cement boards were made using the CO2 injection method. The characteristics of the cement board were tested according to JIS A 5417–1992. The results showed that agathis has good characteristics in terms of mechanical properties. Both Internal bonding and modulus of elasticity were better than others, but not with its modulus of rapture. As for physical properties, parring bamboo actually showed good performance. However, in general, these three species of cement boards did not meet the standard.
Characteristic of Chitosan Adhesive from Shell Shrimp Litopenaeus vannamei and Their Application For Producing Particleboard
Authors: Ningsi D W , Suhasman  , Saad S
Published: August 2019

The shrimp shell that rich compounds of chitin can be converted to produce polysaccharides called chitosan. The chitosan can be utilized as bioadhesive for substitute chemical based adhesive for producing particleboard. The purpose of this study was to evaluate the effect of different concentration acetic acid (CH3COOH) as the solvent to made chitosan adhesive and physical and mechanical properties of the produced particleboard by using sawdust waste. Chitosan adhesive formulation will be used as an adhesive by dissolving chitosan powder with CH3COOH solvent. This research focused on optimization the solvent content wich is CH3COOH in different concentration such as 0.5%, 2% and 4%. Particleboard with size of 25 cm x 25 cm x 0.7 cm with 8%, target density 0.75 g/cm3 were produced using sawdust waste of Paraserianthes falcataria. The processing condition were 180°C in temperature during 12 minutes with pressure of 25 kg/cm2. The research showed, there is no particular trend in particle board characteristics related to solvent concentration. Physical and mechanical Properties fulfill requirement of JIS A 5908-2003 for Moisture Content, MOE and IB. The produced particleboard that using chitosan as bioadhesive and sawdust waste as particle is potentially to be developed technically based on the quality of the particleboards produced.
Mathematical Modelling Time Dependent for Heat Transfer Process in Homogenous Composite ZnO/Activated CNF
Authors: Latief M F , Tahir D , Juarlin E , Suarga
Published: August 2019

A theoretical study of heat transfer on composite Zinc Oxide (ZnO)/Activated Carbon Nanofibers (CNF) by using mathematical model from diffusion equation for stationary composite with various heating time was studied. The equation and boundary conditions are interpreted by using Taylor series expansion to obtain a steady-state numerical solution from the Jacobi iteration algorithm. The composites where put inside the furnace model by filaments on the two sides of the walls as the source of heat (general model for furnace). By using this model, the position of sample to receive the homogeneous temperature determined. We compared the steady-state and unsteady-state conditions to identify the temperature distribution at real-time. The results show that the heat distribution will reach an asymptotic state by performing a numerical analysis is 200 K and 300 K for 25 minute time of heating. In this study, shows the efficient way for annealing homogenous materials to identify the position inside the furnace which can be used as a guide to receive the homogenous temperature during the annealing processes.
Spatial Analysis For Pinus merkusii Land Suitability At Agroforestry Land In Telagah Village Sumatera Utara Indonesia
Authors: Rahmawaty  , Frastika S , Rauf A
Published: August 2019

Pinus (Pinus merkusii) is commonly found in North Sumatra Forest. Community of Telagah Village, Sei Binge Sub District, Langkat, North Sumatera, generally manage the land with agroforestry system. Pinus is the one of agroforestry constituent in the community land in Telagah Village. This study aimed to analyse the suitability of the land for pinus in Telagah Village Sei Bingai Sub District, Langkat District, North Sumatra, Indonesia. This research was conducted on May to September 2018. The survey method was conducted to collect soil samples in the field. Spasial analysis for pinus land suitability was evaluated based on the matching method. The reference and criteria were adopted from the Land Suitability for Agricultural Plants by the Centre for Soil and Agroclimate Research, Bogor-Indonesia. The Geographic Information System (GIS) was used to map the actual and potential land suitability in Telagah Village. The results showed that the actual land suitability classes for pinus in this area were moderately suitable (S2) (97.26%) and marginal suitable (S3) (2.74%). The potential land suitability classes for pinus in this area were Suitable (S1) (52.04), moderately suitable (S2) (46.04%) and marginal suitable (S3) (1.92%) in Telagah Village. The temperature (tc) and erosion hazard (eh) were the dominant of limiting factor in this area.
Performance of Particleboard with Varying Jabon Wood and Andong Bamboo Composition Against Subterranean Termite Attack
Authors: Arsyad W M , Trisatya D R , Sulastiningsih I M
Published: August 2019

This study investigated the effect of mixed material composition of jabon (Anthocephalus cadambaMiq.) and andong (Giganthochloa pseudoarundinaceaeSteud.) particleboards on their resistance to subterranean termite (Coptotermes curvignatusHolmgren). Six types of 35cm × 35cm × 1.2 cm particleboards were produced and glued with phenol formaldehyde in the proportion of 100:0, 70:0, 60:40, 50:50, 40:60 and 30:70 for jabon and andong. Those panels were tested according to SNI 727-2014. The results showed that material composition of jabon and andong was significantly influenced weight loss and termite mortality. Particleboard with 30:70 jabon-andong proportions had the lowest weight loss (4.28%) and classified as resistant class. Termite mortality rate escalated as jabon composition in the panel decreased.
Optimization of SC-CO2 Time Conditions and Permethrin Concentration in Laminated Bamboo Production Using Surface Response Methodology
Authors: Uslinawaty Z , Muin M , Putranto B , Suhasman S
Published: August 2019

Supercritical carbon dioxide method has starting to be used as environmental friendly method in preserving wood. It is expected to maintain physical and mechanical properties of bamboo. The purpose of this study was to determine the effect of the duration times of supercritical conditions and permethrin preservative concentrations on optimization of shear strength of laminated bamboo impregnated by using supercritical carbon dioxide in the initial process (blades) and final process (laminated bamboo). The RSM-CCD experimental design was used to determine the effect of duration times of supercritical carbon dioxide for 20, 25, 30, 35, 40 minutes and the effect of permethrin concentrations 0.1, 0.3, and 0.5% against the shear strength of laminated bamboos. Response surface analysis, using 10 version of design expert software, has been done to get the optimum condition which would produce maximum of shear strength. The results showed that permethrin concentrations have stronger influenced (based on RSM analysis) on the shear strength and durability of laminated bamboo than the times of supercritical carbon dioxide conditions. Optimization of the two combinations of increasing shear strength and endurance were supercritical conditions = 22.71 minutes, and preservative permethrin concentration = 0.24%. Shear strength of shear strength and decrease in combination weight is 85 kg / cm2 and 0.38%.
Medicinal Plant inventory at the Agroforestry Land in Buffer Area of Gunung Leuser National Park
Authors: Rahmawaty  , Amalia R , Batubara R , Rauf A
Published: August 2019

The inventory of medicinal plants in North Sumatra Province are important, especially those that are often utilized by the community. This study aimed to map the distribution of medicinal plants (herbs) under the agroforestry land in buffer area Gunung Leuser National Park. This research was conducted in Simpang Kuta Buluh Village, Sei Bingai Sub District, Langkat District, North Sumatra Province. This research was conducted on March to June 2018. The survey method was used by making plots in the field. A Geographic Information System (GIS) was used to analyze the distribution of the medicinal plants and a Global Positioning System (GPS) was used to record the coordinate points of medicinal plants in the area. The results showed that there were found thirty four (34) species of herbs plant in the area with the total of 307 individuals herb,. Sampelulut (Urena lobata L.) was dominant spesies which is found (56 individuals) in this area, followed by Asar-asar (Selaginella deoderleinii) (42 individuals) and Senduduk Bulu (Clidemia hirta) (30 individuals). Constituent plants in Agroforestry land, namely: Mahoni (Swietenia mahagoni), Durian (Durio zibethinus), Karet (Hevea brasiliensis), Pisang (Musa paradisiaca), Angsana (Pterocarpus indicus), Coklat (Theobroma cacao L.), Petai (Parkia speciosa), Cengkeh (Syzygium aromaticum), Asam Glugur (Garcinia atroviridus, and Kelapa (Cocos nucifera). The data of medicinal plants distribution is vital to provide information for community, researchers, and government.
Improving Degradation Ability of Composite Starch/Chitosan by Additional Pineapple Leaf Microfibers for Food Packaging Applications
Authors: Mutmainna I , Tahir D , Gareso P L , Ilyas S , Saludung A
Published: August 2019

Structural, mechanical properties, and bonding characteristic of plastic bio-composites (starch/chitosan) with an additional Pineapple leaf microfibers (PLM) for 3%, 6% and 9% were carried out by using X-Ray diffraction (XRD), tensile strength test, and Fourier transform infra-red (FTIR) spectroscopy, respectively. The value of tensile strength shows highest for plastic bi-composite with 9% PLM and also XRD spectra shows the amorphous phase with new structure was formed for all bio-composite + PLM. FTIR spectra shows the strong bonding formation as the effect of PLM indicated by increase the intensity of C-H and C=C bond with increasing the amount of PLM. From the biodegradation test shows the PLM strongly influenced to the degradation ability of bio-composite and the highest is for 9% PLM (>80% ). In addition, the lowest browning index is about 37.5% for bio-composite with additional 9% PLM which was determined by using fresh cherry (Muntingia calabura. L). It’s indicated that the plastic bio-composite with an additional PLM shows high potentials for new food packaging applications.
Surface photovoltage spectroscopy of semiconductor materials for optoelectronic applications
Authors: Donchev V
Published: August 2019

The present contribution reviews the basic principles of the surface photovoltage (SPV) spectroscopy in the metal-insulator-semiconductor operation mode emphasizing on the crucial necessity of combined analysis of the SPV amplitude and phase spectra for the understanding and correct interpretation of the experimental data. Several results are presented obtained by the application of the SPV spectroscopy to semiconductor bulk materials and nanostructures designed for applications in optoelectronic devices. These include: (i) AlAs/GaAs superlattices with GaAs embedded quantum wells for optical emitters, (ii) multilayer structures with InAs/GaAs submonolayer quantum dots for infra-red photodetectors, (iii) Si nanowires for light trapping in solar cells and (iv) dilute nitrides Ga(In)As(Sb)N layers for photovoltaic applications. Valuable information about the investigated materials is obtained such as the optical absorption spectrum defined by the quantum confinement and excitonic effects, the optical transition energies, the effect of surface states on the minority carrier diffusion length, the type of the residual doping in the layers, and the alignment of the energy bands across the structures. It is shown that the SPV spectroscopy is a powerful highly sensitive non-destructive technique for room temperature characterization of various semiconductor materials applied in optoelectronics.
Causality in quantum field theory with classical sources
Authors: Skagerstam Bo-Sture K , Eriksson Karl-Erik , Rekdal Per K
Published: August 2019

In an exact quantum-mechanical framework we show that space-time expectation values of the second-quantized electromagnetic fields in the Coulomb gauge in the presence of a classical conserved source automatically lead to causal and properly retarded ℏ-independent electromagnetic field strengths. The classical ℏ-independent and gauge invariant Maxwell’s equations naturally emerge in terms of quantum-mechanical expectation values and are therefore also consistent with the classical special theory of relativity. The fundamental difference between interference phenomena due to the linear nature of the classical Maxwell theory as considered in, e.g., classical optics, and interference effects of quantum states is clarified. In addition to these issues, the framework outlined also provides for a simple approach to invariance under time-reversal, some spontaneous photon emission and/or absorption processes as well as an approach to Vavilov-Čherenkov radiation. The inherent and necessary quantum uncertainty, limiting a precise space-time knowledge of expectation values of the quantum fields considered, is, finally, recalled.
Portugal under austerity: from financial to renewable crisis?
Authors: Andreas Jan-Justus , Burns Charlotte , Touza Julia
Published: August 2019

Portugal was hit hard by the global financial crisis, with concomitant effects upon the development of its renewable energy sector. The imposition of austerity has had negative impacts upon the further development of the Portuguese renewables sector, prompting the question of whether we have seen a critical juncture that will lead to a new policy trajectory. Historical institutionalist analysis demonstrates a range of unintended consequences arising from the pursuit of austerity in Portugal, yet no true critical juncture to the country’s commitment to renewable electricity. The path dependent structure of the Portuguese electricity market and the export bottleneck between the Iberian Peninsula and Central Europe are identified as critical variables explaining the sub-optimal policy trajectory. We conclude that resolving this bottleneck will be critical for Portugal to reduce current financial and electricity price pressures, and continue its renewable energy transition.
The relationship of cognitive change over time to the self-reported Ascertain Dementia 8-item Questionnaire in a general population
Authors: Passler Jesse S , Kennedy Richard E , Crowe Michael , Clay Olivio J , Howard Virginia J , Cushman Mary , Unverzagt Frederick W , Wadley Virginia G
Published: August 2019

Objective

The aim of the study was to examine the relationship between longitudinally assessed cognitive functioning and self-reported dementia status using the Ascertain Dementia 8-item questionnaire (AD8) in a national population-based sample.

Methods

The analysis included 14,453 participants from the REasons for Geographic and Racial Differences in Stroke study. A validated cutoff of ≥2 symptoms endorsed on the AD8 (administered 10 years after enrollment) represented positive AD8 status. Incident cognitive impairment was defined as change from intact to impaired status in the Six-Item Screener score, and cognitive decline was defined by trajectories of Letter “F” Fluency from the Montreal Cognitive Assessment, and Animal Fluency, Word List Learning, and Word List Delayed recall, all from the Consortium to Establish a Registry for Alzheimer’s Disease battery. Logistic regression models controlled for demographics, health variables, and depressive symptoms.

Results

Sensitivity and specificity of the AD8 to detect incident cognitive impairment were 45.2% and 78.4%, respectively. Incident cognitive impairment and a one-word decline in WLL increased the odds of self-reported positive AD8 by 96% (95% CI: 1.68–2.28) and 27% (95% CI: 1.17–1.37), respectively. There was a strong association between high depression risk and self-reported positive AD8 in sensitivity analyses.

Conclusions

Incident cognitive impairment and high depression risk were the strongest predictors of self-reported positive AD8 in this population-based sample. Our results inform the utility of the AD8 as a self-report measure in a large, national sample that avoids selection biases inherent in clinic-based studies. The AD8 is screening measure and should not be used to diagnose dementia clinically.
MOOMIN – Mathematical explOration of ’Omics data on a MetabolIc Network
Authors: Pusa Taneli , Ferrarini Mariana Galvão , Andrade Ricardo , Mary Arnaud , Marchetti-Spaccamela Alberto , Stougie Leen , Sagot Marie-France
Published: August 2019

Motivation

Analysis of differential expression of genes is often performed to understand how the metabolic activity of an organism is impacted by a perturbation. However, because the system of metabolic regulation is complex and all changes are not directly reflected in the expression levels, interpreting these data can be difficult.

Results

In this work, we present a new algorithm and computational tool that uses a genome-scale metabolic reconstruction to infer metabolic changes from differential expression data. Using the framework of constraint-based analysis, our method produces a qualitative hypothesis of a change in metabolic activity. In other words, each reaction of the network is inferred to have increased, decreased, or remained unchanged in flux. In contrast to similar previous approaches, our method does not require a biological objective function and does not assign on/off activity states to genes. An implementation is provided and it is available online. We apply the method to three published datasets to show that it successfully accomplishes its two main goals: confirming or rejecting metabolic changes suggested by differentially expressed genes based on how well they fit in as parts of a coordinated metabolic change, as well as inferring changes in reactions whose genes did not undergo differential expression.

Availability and implementation

github.com/htpusa/moomin.

Supplementary information

Supplementary data are available at Bioinformatics online.