Land use/cover dynamics and their effects in the Gerado catchment,northeastern Ethiopia

This paper analyses the land use/cover dynamics of land degradation through the interpretation of aerial photographs (1958 and 1980) and 2006 SPOT-5 satellite image of the Gerado catchment. Other, non-visual data were gathered from personal interview and focus group discussions conducted in 2010 and 2011 with local elders, farmers and development (agricultural extension) agents. The results identified the presence of cultivated and rural settlement land, shrubland, woodland, bare land, grassland, urban built up area and forest. Throughout the period 1958–2006, urban built-up area, forest and cultivated and rural settlement land expanded at an average rate of 6.85%, 1.85% and 0.14% per year at the expense of shrub, wood and grasslands, which declined by 0.77%, 0.21%, 0.65% per year, respectively. The land use/cover dynamics of 1958–2006 resulted in the reduction/loss of biodiversity, occurrence of high soil erosion and ramification of gullies. The triggers for these changes were population growth, land cultivation, expansion of farmland, inappropriate land management, civil war and fuel wood demand. These led to further land degradation and more food insecurity among many farming households. Land resources have to be used according to their suitability. Thus, the exposed and steep mountains of the area have to be protected from cultivation and should be re-afforested. The paper discusses other implications for management and policy formulation also.     

Floristic diversity with particular reference to endemic,rare or endangered flora in forest formations of Saïda (Algeria)

An evaluation and inventory study on the natural vegetation cover and its diversity was carried out on the forest vegetation of the district of Saïda. The floristic diversity of our study area revealed the existence of 397 taxa belonging to 64 families and 271 genera. The most important families are Asteraceae (42 genera), Fabaceae (25 genera), Brassicaceae (22 genera) and Poaceae (22 genera). The category of rare taxa represents 13% of the studied flora (52 taxa). In our study area, we have counted 35 endemic regional species of which 19 species are endemic Algerian-Moroccan, and 3 species are strictly endemic to Algeria. Among the taxa analysed, 02 are included in the IUCN Red List, and 12 are on the Algerian list of protected non-cultivated plant species.     

A neural network bid/no bid model: the case for contractors in Syria

Despite the crucial importance of the ‘bid/no bid’ decision in the construction industry, it has been given little attention by researchers. This paper describes the development and testing of a novel bid/no bid model using the artificial neural network (ANN) technique. A back‐propagation network consisting of an input buffer with 18 input nodes, two hidden layers and one output node was developed. This model is based on the findings of a formal questionnaire through which key factors that affect the ‘bid/no bid’ decision were identified and ranked according to their importance to contractors operating in Syria. Data on 157 real‐life bidding situations in Syria were used in training. The model was tested on another 20 new projects. The model wrongly predicted the actual bid/no bid decision only in two projects (10%) of the test sample. This demonstrates a high accuracy of the proposed model and the viability of neural network as a powerful tool for modelling the bid/no bid decision‐making process. The model offers a simple and easy‐to‐use tool to help contractors consider the most influential bidding variables and to improve the consistency of the bid/no bid decision‐making process. Although the model is based on data from the Syrian construction industry, the methodology would suggest a much broader geographical applicability of the ANN technique on bid/no bid decisions.     

Developing a procurement path determination chart SEM-based approach

The choice of an appropriate procurement system is crucial to construction project success. Procurement selection is largely based on path determination charts, with at least eight key criteria needing to be weighted by decision-makers. Including certain criteria whilst ignoring client-borne transaction costs (TCs) resulting from environmental uncertainties simplifies this process. TCs are ‘unseen’ costs associated with pre- and post-contract work. The effects of uncertainties in the transaction environment and procurement systems on TCs are investigated, comparing the traditional and design-build procurement systems. A cross-sectional sample approach was deployed, involving survey questionnaire and results verification through ‘real-world’ cases. Data was sought from construction professionals in management, design and operation of construction projects. The research participants evaluate their time spent on procurement activities using a five-point Likert scale. Hypotheses of the relations between environmental uncertainties, procurement systems, and pre- and post-contract TCs are tested using a structural equation modelling (SEM) approach. The study found that TCs account for about 46.75% and 42.88% of the daily time spent by project managers in traditional and design-build procurement systems in New Zealand respectively. The study concludes that the TC concept is a useful framework for determining objective instead of subjective opinions for procurement decisions.     

Challenges Upon Reactive Plasma Spray Nitriding: Al Powders and Fabrication of AlN Coatings as a Case Study

Reactive plasma spraying (RPS) is a promising technology for the in situ formation of several ceramic coatings. The focus of this paper is to summarize the state of our current knowledge about the RPS process and using the nitriding of Al particles and the fabrication of aluminum nitride coatings, as a case study. The aspects and challenges in this process such as the influence of the plasma power, in-flight time, particle size, nitriding mechanism, splat morphology, in-flight particle diagnostics, N₂ plasma gas, and the feeding rate on the RPS process are analyzed and discussed.     

Rheology of natural fibers thermoplastic compounds: Flow length and fiber distribution

The presented study investigates the flow length and the corresponding fiber content distribution in the injection‐moulded natural fiber reinforced thermoplastics and its relation to fiber type and processing parameters such as injection pressure, temperature, injection rate and mould tempering by increasing die temperature. In this research, polypropylene compounds with nominally 30 wt % hemp and sisal fibers are investigated. The influence of the injection pressure (500 and 1000 bar), melt temperature (180°C, 200°C, and 220°C), and die temperature (23°C and 80°C) on the fiber content distribution all over the sample is investigated. An increasing linear trend of fiber content along the spiral length is observed as an evidence of a fiber/polymer multiflow system. A pattern for fiber content distribution with respect to the fiber length along the injected spiral can be distinguished, where the longer fibers are usually found at the end of the injected part and the shorter fibers remain near mould entrance point. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39861.     

On optimal filters with maximum number of constraints on amplitude and phase characteristics

For optimal filters specified amplitude and phase (or group delay) characteristics, it is required that all the free parameters of the transfer function be used for the approximation. To achieve this requirement, the number of constraints on the amlitude and phase characteristics is defined first on general interpolation bases. Constant or arbitrarily prescribed lowpass or bandpass group delay and amplitude characteristics are approximated in the maximally flat, ripple or mixed sense for lumped filters, whereas highpass and band rejection characteristics are also considered for distributed or sampled data filters. The relationship between the number of free parameters and the number of amplitude and phase constraints for a given degree is derived for non-reciprocal as well as for reciprocal lossy and reciprocal reactant cases. Conditions are derived for the distribution of free parameters between the passband and stopband amplitude and phase characteristics for transfer functions with Hurwitzian denominator and also for monotonic amplitude characteristics in the transition band. Some published separate and simultaneous approximation methods are evaluated and compared on the above bases. It is pointed out that some of these methods do not satisfy the above requirements, although the optimal solution would exhibit higher performances.     

The glass transition temperature of nitrated polystyrene/poly(acrylic acid) blends

Low-molecular-weight polystyrene was nitrated to different levels. The nitrated polystyrene was blended with different molecular weights of poly(acrylic acid), PAA. The glass transition temperatures (T_g) for the mixtures were investigated by differential scanning calorimetry. A single T_g was observed for all blends, indicating single-phase blends. In general, it was found that the T_g increases with molecular weight of PAA. The T_g values of the blends showed a positive deviation from the linear average T_g as a result of strong hydrogen bonding between the segments of the component polymers. The observed T_g values were not adequately represented by simple predictive equations or by single-parameter fitting equations. However, two-parameter fitting equations gave a reasonable representation of the data.     

Impact of Coronavirus Pandemic Crisis on Technologies and Cloud Computing Applications

In light of the coronavirus disease 2019 (COVID-19) outbreak caused by the novel coronavirus, companies and institutions have instructed their employees to work from home as a precautionary measure to reduce the risk of contagion. Employees, however, have been exposed to different security risks because of working from home. Moreover, the rapid global spread of COVID-19 has increased the volume of data generated from various sources. Working from home depends mainly on cloud computing (CC) applications that help employees to efficiently accomplish their tasks. The cloud computing environment (CCE) is an unsung hero in the COVID-19 pandemic crisis. It consists of the fast-paced practices for services that reflect the trend of rapidly deployable applications for maintaining data. Despite the increase in the use of CC applications, there is an ongoing research challenge in the domains of CCE concerning data, guaranteeing security, and the availability of CC applications. This paper, to the best of our knowledge, is the first paper that thoroughly explains the impact of the COVID-19 pandemic on CCE. Additionally, this paper also highlights the security risks of working from home during the COVID-19 pandemic.