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Automated agricultural machinery has advanced significantly in the previous ten years; however, the ability of such robots to operate safely will be critical to their commercialization. This study provides a holistic evaluation of the work carried out so far in the field of automated agricultural machines’ safety, as well as a framework for future research considerations. Previous automated agricultural machines’ safety-related studies are analyzed and grouped into three categories: (1) environmental perception, (2) risk assessment as well as risk mitigation, and (3) human factors as well as ergonomics. The key findings are as follows: (1) The usage of single perception, multiple perception sensors, developing datasets of agricultural environments, different algorithms, and external solutions to improve sensor performance were all explored as options to improve automated agricultural machines’ safety. (2) Current risk assessment methods cannot be efficient when dealing with new technology, such as automated agricultural machines, due to a lack of pre-existing knowledge. Full compliance with the guidelines provided by the current International Organization for Standardization (ISO 18497) cannot ensure automated agricultural machines’ safety. A regulatory framework and being able to test the functionalities of automated agricultural machines within a reliable software environment are efficient ways to mitigate risks. (3) Knowing foreseeable human activity is critical to ensure safe human–robot interaction.

The aim of this project is to design a solar thermal absorption air conditioning system that operates under UAE climate conditions. In absorption system, compressor which is normally used in conventional AC system, replaced by a chemical cycle that consists of a generator, absorber, pump, and expansion valve, while the rest of the components such as the evaporator, condenser, and expansion valve remain the same as conventional AC system. In this design, the water and lithium bromide pair is used as a refrigerant and absorbent, respectively. The generator is driven by an evacuated solar collector to heat the lithium bromide in the chemical cycle, while a solar PV panel, which ensures that the system works 100% by solar energy, drives the pumps and fans. An energy storage device also incorporated in the system to run it round the clock. An experimental investigation of the proposed design is presented in the paper. Results suggest that the proposed design match well to meet the cooling load demand which was about 300 watts. Furthermore, the system able to provide a desired as well as uniform comforts temperature at about 23 °C inside the room. The system COP was calculated to be 0.51. Life cycle analyses were also carried out using Eco Audit CES Edu pack software to study the viability of the new design. The results showed that the proposed new system is economically viable and environmentally friendly. Keywords: Absorption cooling, Water–liBr, Solar energy, Solar PV, COP, Life cycle analysis

Photovoltaic (PV) solar panels are one of the most important sources of renewable energy. The life cycle analysis is a tool used to evaluate components or systems in terms of cost and environmental impact. This paper discusses the life cycle analysis for PV solar panels technology. Two distinct technologies of cells based on single crystalline silicon (reference) and polycrystalline gallium were studied. The reference cell material, manufacturing process, maintenance, transport, disposal and end of life (EOL) potential were analyzed during the lifetime of the solar panel. The analysis focused on three main elements: the energy consumption, the CO 2 footprint and the cost for all phases of the life cycle process. The materials used, maintenance, transportation, manufacturing processes, disposal, EOL potential were also discussed in detail for both technologies. The results showed that a change in the material has a massive influence on the total energy consumption, CO 2 footprint, and cost. These values were 7.35 × 1010 J, 0.510 metric ton of CO 2 and the US $ 584, respectively, for reference cell (silicon) whereas for Gallium the values were 7.7 × 1010J, 0.717 metric ton CO 2 and US $ 986, respectively.

Hybrid PV- thermal system (PV/T) is used to harvest both electrical and thermal energy from solar radiation. Using a hybrid PV/T system improves the electrical efficiency of the PV module while the thermal energy can be used for various heating applications. The aim of this work is to numerically study the performance of the PV/T system in a hot climate condition. The cooling system of PV/T consists of several channels parallel to each other. A novel three-dimensional numerical simulation of the system was performed to study the thermal efficiency. The standard k-epsilon turbulence model was used during the simulation. This novel system was based on applying different thermal boundary conditions on the sides of one channel rather than simulating the whole cooling system. Using one channel simulation allows the creation of a smaller number of meshes, hence, reduces the computational time. The thermal efficiency of the PV/T system was calculated using the superposition method for different mass flow rates. The results showed an increase in the thermal efficiency from 60% up to 68% by increasing the mass flow rates from 0.4 - 5.4 L/min. These results were in good agreement with the results in the literature.

The assessment of fuel cell stacks is crucial for the development of fuel cells as renewable energy sources. This development is triggered by the search for cleaner, environmentally friendly and more efficient energy generation. The goal is to provide sustainable energy requirements of the present without compromising the availability of energy resources for future generations. In this paper, a life cycle assessment for a proton exchange membrane fuel cell (PEMFC) stack with different materials for hydrogen storage tanks is carried out. To the knowledge of the authors, few studies have been reported in this area. This assessment analyzes the materials used, the amount of energy, carbon footprint, and the cost of PEMFC stack. It is also aimed at reducing the impacts of the preceding factors by the proper selection of the material that maximizes the efficiency of the fuel cell stack at a minimum cost. In addition, the objective is to select the manufacturing process that has less emission production without compromising the fuel cell stack efficiency. Furthermore, a study on the hydrogen storage tank material is proposed. A comparison between stainless steel, aluminum and three-layer material based on polymer liner, carbon fiber reinforced polymer, and glass fiber reinforced polymer layers for hydrogen storage tank is presented. The stack consists of four cells with a lifetime of at least 2 years and 17 W power. The results show that the usage of PEMFC stack with a stainless steel hydrogen storage tank appears to be a safer option for the environment.

This work presents a novel solar powered air-conditioning system that operates under UAE climate conditions. Distinct passive techniques and refrigerant-based nanofluids, termed as ‘‘Nano refrigerants’’ were investigated to enhance the system performance. Results suggest that the proposed design of using passive techniques such as: roofing reflective material, trees, double-glazed windows, and overhang, reduces the space cooling load by 31.5%. Nano refrigerants effect on the coefficient of performance (COP) resulted in improving COP by adding of 5 vol % single wall carbon nanotube (SWCNT) into R407c refrigerant at temperatures of 283–308 (K). The results indicate that the thermal conductivity of SWCNT/R-407c nano refrigerant increased by about 15.6% compared to the base refrigerant (R-407c) at 305 K. The usage of nano refrigerant reduces consumption of compressor work by 4%. Furthermore, SWCNT/R-407c nanorefrigerant shows the notable improvement of COP of at about 17.02% for thermal conductivity and at about 10.06% for specific heat, respectively compared to R-407c refrigerant. Finally, comparisons between the proposed design and the conventional system as well as with previous literature. Results demonstrate that the proposed system reduces the compressor work by 34% and the COP is increased by 4.59% compared to the conventional air-conditioning system. Keywords: Nanoparticle, Nanorefrigerent, Solar energy, Passive technique, HVAC system, COP

The present research aimed at analyzing the knowledge of whitefly comprehensive control method among tomato growers in two villages of Abu Homus district at Behira governorate. Abu homus was selected as one of the major areas for tomato plantations, and the villages of Botoros and Jawad Hosney were chosen for they have concentrated tomato plantations that witness large outspreads of whitefly infestation. The data were collected through questionnaire during interview of a random sample of 124 growers according to Crigssy and Morgan equation. The statistical methods applied in the study were; mean, repeated charts, percentage, Pearson's correlation, and multiple regression. The results show that: 82.26% of the respondents have low and medium knowledge of the tomato whitefly comprehensive control method and they suggest a significant positive relation between the respondents' knowledge degree of the tomato whitefly comprehensive control method and the following; total area planted with vegetables, total area planted with tomato, level of knowledge of the damages resulting from using pesticides in vegetables pests control and the level of participation in extension activities (p 0.01). There was a significant positive relation between the dependent variable and the number of education years (p0.05). The following variables had positive impact; number of years of education, total area planted with vegetables, total area planted with tomato, level of participation in extension activities (p0.01) based on the calculated t values (-3.167, 2.619, 2.424 and 5.224) respectively. Also these variables account for 58% of the changes in respondents' degree of knowledge of the tomato whitefly comprehensive control method based on R2 value, that is, 0.576. Cucumber growers had several problems upon applying the tomato white fly comprehensive control method including; high process of control pesticides, lack of pesticides alternatives, not applying farming circulations systems for tomato, growing whitefly hosting plants next to tomato such as cucurbits, applying pesticides in not suitable times and lack of good application equipment, small number of extension fields applying tomato whitefly comprehensive control method.

The aim of this study was to investigate the spatial variability in degradation and mineralization of atrazine and isoproturon in subsurface samples taken from sandy loam soils overlying gravel terraces which form part of a groundwater protection zone. Percussion drilling was used to obtain samples from 11 boreholes (maximum depth 3 m). Unlabelled atrazine or isoproturon, and ring-14C-labelled atrazine or isoproturon were added to samples, incubated at 25 degrees C for up to 16 weeks, and analyzed for the residual herbicide or [14C]carbon dioxide. All samples showed the potential to degrade these herbicides, although the percentage degradation decreased by a factor of 2-3 from the surface soil to a depth of 3 m. This was associated with a decrease in organic matter content, but there was no change in the potential to mineralize acetate, indicating that specific changes in the catabolic ability of the microbial population occurred with depth. The capacity of samples to mineralize atrazine and isoproturon to carbon dioxide decreased markedly with depth, with no mineralization potential observed at a depth of 80 cm.

The potential for degradation of atrazine or isoproturon in the unsaturated zone of two boreholes was studied under laboratory conditions. Intact and uncontaminated samples were obtained from regular depths of 0-16.45 m and 0-9 m using a percussion coring technique. The results showed that the deep unsaturated zone contained micro-organisms capable of degrading atrazine or isoproturon. The rate of degradation was much faster in surface soil than in most unsaturated materials of both boreholes. The amount of atrazine remaining six months after incubation also varied between the two boreholes. A relatively small amount of atrazine was lost from sterilised samples, suggesting a significant role for microbial degradation. The addition of nutrient and energy sources into materials of low degradation capacity did not enhance the degradation of atrazine. Degradation rate was more related to the presence of a competent microbial population rather than to the presence of indigenous organic matter. However, the competent micro-organisms are more likely to be present when the organic matter content is high. The type and activity of these micro-organisms and their physical environment may have considerable influence on atrazine degradation and are likely to be responsible for much of the variation in the rate of degradation observed at different depths.

The influence of different moisture and aeration conditions on the degradation of atrazine and isoproturon was investigated in environmental samples aseptically collected from surface and sub-surface zones of agricultural land. The materials were maintained at two moisture contents corresponding to just above field capacity or 90% of field capacity. Another two groups of samples were adjusted with water to above field capacity, and, at zero time, exposed to drying-rewetting cycles. Atrazine was more persistent (t(1/2) = 22-35 days) than isoproturon (t(1/2) = 5-17 days) in samples maintained at constant moisture conditions. The rate of degradation for both herbicides was higher in samples maintained at a moisture content of 90% of field capacity than in samples with higher moisture contents. The reduction in moisture content in samples undergoing desiccation from above field capacity to much lower than field capacity enhanced the degradation of isoproturon (t(1/2) = 9-12 days) but reduced the rate of atrazine degradation (t(1/2) = 23-35 days). This demonstrates the variability between different micro-organisms in their susceptibility to desiccation. Under anaerobic conditions generated in anaerobic jars, atrazine degraded much more rapidly than isoproturon in materials taken from three soil profiles (0-250 cm depth). It is suggested that some specific micro-organisms are able to survive and degrade herbicide under severe conditions of desiccation.

Transparent polymers are widely used in building test models and producing operation sensors. The diversity in the parameters of the modulated electromagnetic waves, when travelling through a polymeric medium in the form of a light vector, is the means of carrying information in most of the optical sensors. Therefore, the development of efficient operation sensing instrumentation relies basically on a solid understanding of the mechanical, chemical, and physical characteristics of the polymers involved. Optical anisotropy has been shown to prevail in commercially available polymers. This physical phenomenon may lead to erroneous results if not encountered while processing the acquired optical data. The presence of residing double refraction seem to be advantageous in numerous cases. The disadvantage of weak birefringence can be removed. Thus, a relatively cheap material, such as acrylic, may be upgraded to an excellent material for building optical strain gauges. This present contribution presents a brief review of the beneficial and adverse effects of the orientation of the chains in polymers, on the penetrating dielectric vector.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.