Журнал гражданской и экологической инженерии

In this study, the effect of silicon dioxide nano particle and fly-ash on the permeability of sand were investigated. For this purpose, various combinations of fly ash and sand were investigated to examine the impact of mixing of fly with sand. We can make a least permeable mass by mixing 80% of fly ash with 20% sand. According to specific gravity of sand, fly ash, nano silica and weight of the mould with a porosity of 0.4 these materials has been mixed manually. Fly ash is mixed with the fine sand in increasing proportions of 5%, 15%, 25%, 35%, 45%, 55%, 65%, 75%, 85%, 100%. According to the results of present study, 80% fly ash mixed with 20% sand provides the least permeable combination compared to the rest. The percentage-mix of fly ash and sand is taken different from previous study but least combination was achieved with a similar combination of 80% fly ash and 20% sand which was also reported by Gupta and Alam 2004. To make the least permeable sample to almost impermeable, nano silica mixed with least permeable sample in increasing percentage by 5%, 7.5%, 10% and 12.5%. A falling head and constant head method was used to test all samples for hydraulic conductivity.

Results of present study revealed that when 20% of sand mixed with 80% of fly ash gives value of permeability (6 × 10^-05 cm/s) which are 86 times lower than the permeability of sand.

It was observed that a mixture of 20% sand and 80% fly ash mixed with 12.5% of nano silica gives a permeability (2.20 × 10^-06 cm/s) i.e in the range of clay which is 2340 times lower than the permeability of sand.

The permeability property was found to be highly improved on addition of fly ash and nano particles to sand.

Comprehensive results proving the improvement in the permeability properties have been obtained in the specimen containing 12.5% nano silica with least permeable sample of fly ash–sand mixture.

Over 90% of the world's natural gas hydrate (NGH) is contained in fine-grained reservoirs. These reservoirs can be found all over the world. However, conventional methods make it difficult to economically and environmentally exploit this kind of NGH reservoir. Because the production process does not depend on mass and heat transfer within the formations, water-jet cutting is a method for mining such hydrate reservoirs that is both effective and good for the environment. The purpose of this work was to clarify the erosion performance of marine hydrate-bearing sediment (HBS) impacted by water jets through a series of physical experiments. According to the findings, water jet vertical erosion of HBS is severely hampered by the accumulation of sediment and hydrate particles at the bottom of the erosion hole. The optimal jet distance for a given jet flow rate is between 4 and 28 millimetres. Additionally, the erosion of the hole's top is significantly affected by the upwelling flow of solid particles. Erosion holes take on the shapes of a gourd and a bamboo in reservoirs with high hydrate saturation (60–80%) and low hydrate saturation (20–40%), respectively. In addition, jet distance and hydrate saturation are less affected by jet flow rate variation than volume erosion efficiency and depth erosion efficiency.

In refractive surgery, solid-state lasers emerged as an alternative to excimer systems at the beginning of the 2000s. Solid-state laser systems were capable of producing excellent clinical outcomes despite some of the limitations imposed by technology at the time. The clinical outcomes of five eyes treated by a new solid-state laser system in three patients are reported in this prospective case series. Prior to surgery, corneal top andtomography, aerometry and confocal microscopy were used to examine the patients. After undergoing a refractive treatment with the solid-state ablation laser and a femtosecond LASIK procedure with the Ziemer LDV Z8, each patient was followed up for up to a year. None of the operated subjects showed any higher-order or spherical aberrations when the aspheric optimized profiles were used. During the follow-up, no BCVA lines were removed from any of the eyes. The safety index for patient 1 was 5 six months after surgery, while it was equal to 1 for patients.

To investigate the spatio-temporal expansion of the town and its impact on the livelihood of urban fringe agricultural community, the study was made on land transformation analysis in between 1984 and 2015. The main objective of the study was to assess the impact of urban expansion on livelihood of urban fringe of Ambo town as a result of land use change in pre urban area of the town. The 1984 and 2011 administrative boundary maps of the town were used to analyze the extent of area expansion of the town. During this period the town was expanded from 1020.220 ha to 8421.75 ha indicating that the net expansion of the town over the study years was about 7351.1062 ha with about 237 ha increment yearly within 31 years. This boundary expansion of the town directly or indirectly affecting the livelihood of the urban fringe agricultural community of the town. Predominantly at the expense of croplands in the hinterlands, built-up area was increased from 307.44 ha (in 1984) to 913.05 (in 2015). Beside to this, the productive farmland of the urban fringe of the town was decreased from 6651.65 ha (in1984) to 5625.75 ha in 2015. Land cover transformation analysis in between 1984 and 2000 the built-up area expansion was contributed by 451.6675 ha and 60.75 ha conversion of cropland and vegetation area respectively while cropland and vegetation area was negatively affected by 176.085 and 173.9703 ha respectively from its previous area coverage. A household survey was conducted on 146 households with different demographic composition through systematic and purposive sampling techniques. The data were collected from both primary and secondary data sources and analyzed using descriptive statistics and had arrived at conclusion that horizontal urban expansion has adverse impact on livelihood of urban fringe farming community. The analyzed information also indicates that the possession assets and hence annual income of dislocated farmers were declined due to declining their asset possession they had. The evidence from the sampled house hold shown that the majority (82.90%) of household heads’ annual income was below 5000 ETB indicating that majority of the affected community’s livelihood is not beyond subsistence way of life. This indicated that the intervention of governmental and non-governmental organizations should be needed to support the dislocated households financially and technically to make sustainable life and adaptive strategies with the change occurred.

Railway transportation is nowadays becoming one of the most preferred mode of transport due to its safety, capacity and reliability; the capital cost for the construction of the railway infrastructure is however very high and is characterized by high rigidity as the track layout is fixed; therefore there is need to optimally use the available infrastructure. Minor delays arising from a simple disruptions or even a single train failure can have massive impacts in terms of overall delays for subsequent trains using the track facility if not solved amicably. Disruptions can be attributed to power outages, mechanical failures, derailments, accidents or even environmental factors.

In a case of multiple uncertain perturbations happening in a busy complex railway network, where there are many trains requesting to use the available track resources concurrently, there will be massive delays which has a lot of negative operational and economic implications as well as passengers’ dissatisfaction. A mathematical model that is; a mixed integer linear programming formulation is modelled to minimize total time delays in case of a set of multiple disruptions occurring on a busy track section i.e. bottleneck section, the model is formulated with consideration of sets of constraints factoring in feasible routes and safety margins and other operational dynamics such as dwell times to achieve optimal use of the available infrastructure.

A number of numerical experiments based on arbitrary data and real network data are carried out to verify the effectiveness and efficiency of the proposed model. Performance of the designed model is evaluated and results are validated, the results obtained shows that the model offers an efficient rescheduled trains operation plan during disruptions, furthermore the performance of Fmincon solver and Genetic Algorithms (GA) are compared and their robustness evaluated, GA shows better performance during multiple disruption scenarios.

Microplastics (MPs) pollution is a most burning concern as they pose threats to marine organisms and their ecosystem. However, there is limited information for MPs availability in the marine environment, especially in Pakistan. The current study was conducted with the objective of investigating microplastic number, shape and color in the water and sediments of Ras Zarrin, Ras Juddi, Pasni Creek and Ormara beach and Astola Island. Comparisn of MPs contamination in the first marine protected area (Astola Island) and other coastal areas of Balochistan. Our results demonstrated that greater concentration of microplastics in the sediments as compared to water samples. According to this study, the most polluted areas in the following order Astola Island>Ras Juddi>Ormara beach>Pasni creek>Ras zarrin. In water samples the number of micro plastics investigated 9 items/100 L as compared to sediments 103 items/10 g. The dominant colors were black, blue, green, red and white. Size ranges (1 mm to 5 mm) and has shape of fibers and fragments mostly. This research study highlights the need of proper plastic waste management system and should be create awareness to the local residents, tourists and stakeholders about plastic pollution catastrophes in these areas.