Artificial Fences Research Articles

Қарнақты бекітпелермен жоғары кернеулерден контурға жақын массивінің геомеханикасын бақылау арқылы қайта пайдаланылатын дайындау қазбаларының тұрақтылығын арттыру

An analysis of existing methods and means to improve the sustainability of reused development workings has been made. to protect the workings on the border with the goaf permanent artificial fences should be used: organ rows, bushes of racks, bonfires made of sleeper timber filled with rock, bonfires with an organ row, organ rows with a rubble strip, supports of high strength and limited compliance, etc. and portable protective supports made of metal friction struts, hydraulic struts, etc. The following factors are accepted as influencing factors: the presence of zones of increased rock pressure; strength characteristics of the rocks of the roof and soil of the formation and their thickness; structure and water saturation of rocks; landing step of the main roof; the presence of disjunctive geological disturbances; lava movement speed; power characteristics of the lining of the excavation. The output parameters are: the magnitude of the heaving of the formation soil, the deformation of the elements of the lining of the mine working; breaks in the interlocks of the support, displacement of the working contour in the vertical and horizontal plane, displacement of the side arched legs into the working cavity, etc. All these parameters were considered from the point of view of the need to invest in the development of material and labor costs to bring it into an acceptable operational condition. The nature of the pressure distribution depends on the extracted thickness of the reservoir, for example, the displacement and convergence of roof and soil rocks with an increase in reservoir thickness from 1.0 to 2.0 m increase, on average, by 10-20%. The results of the analysis indicate more "heavy" conditions for maintaining the workings, formed behind the lava by 1.3-2.5 times and reused 1.7-3.5 times compared to the undercut and workings made in the coal massif.

Effects of Long-Term Exclosure on Main Plant Functional Groups and Their Biochemical Properties in a Patchily Degraded Alpine Meadow in the Source Zone of the Yellow River, West China

This study aimed to understand the response of vegetation community characteristics in the degraded alpine meadow of the Source Zone of the Yellow River to exclosure of various lengths. Artificial fences were erected to prevent livestock grazing and let the degraded meadow recover naturally as a means of restoration. The research focused on a typical degraded alpine meadow in which four plots were fenced off for three periods of 1 year (E1), 4 years (E4), and 10 years (E10), plus a freely grazed plot as the control. The study compared and analyzed the differences in plant community characteristics, carbon (C), nitrogen (N), and phosphorus (P) reserves, as well as the stoichiometric characteristics of main functional groups in the alpine meadow over different exclosure durations. The results indicated that E10 long-term exclosure significantly increased the aboveground biomass of gramineous plants but reduced the aboveground biomass of miscellaneous grasses. However, when compared to E4 short-term exclosure, E10 resulted in a reduction in the aboveground biomass of Cyperaceae plants. On the other hand, E4 medium-term exclosure significantly increased the aboveground biomass of Gramineae and Cyperaceae. Exclosure significantly increased the nitrogen (N) and phosphorus (P) reserves of the aboveground plant communities. Among these communities, the plant communities in the E10 long-term exclosure had the highest N and P reserves. However, this exclosure length also led to a significant reduction in plant diversity. Furthermore, except for Cyperaceae, all functional groups were observed in E10 and E4 plots. The carbon–nitrogen ratio and carbon–phosphorus ratio of these groups were significantly lower than those of groups G and E1. Medium-term exclosure (E4) has a positive impact on the aboveground biomass as well as plants’ nitrogen and phosphorus reserves. However, long-term exclosure (E10) has been observed to decrease species diversity and nutrient utilization efficiency of alpine meadow vegetation, which can be detrimental to the sustainable development of the alpine meadow ecosystem. Therefore, it is not recommended to implement long-term exclosure. Instead, a moderate level of grazing should be adopted after 4 years of exclosure.

Development of sustainable solutions to sand encroachment on roads in Kuwait using numerical modeling

Site reconnaissance of the threat of sand encroachment in Kuwait outlined major roads that were closed or partially closed for long periods of the year. These roads are AlSubia, AlWafra–Mena Abdallah, and AlWafra-AlZoor. Site surveys of the affected roads were undertaken to investigate the types and thicknesses of accumulated sand layers that were exposed to wind erosion. Soil samples were also collected to assess the particle size distribution. Wind data over the past 35 years were analyzed, which indicated that the prevailing direction is northwest with an average speed of 6–8 m/s. A preliminary concept design based on a composite system of natural and artificial elements was developed to be a sustainable protective system, which included double porous fences and green belts as major elements. Testing of the concept design model was performed in a virtual wind tunnel with different fence porosities and afforestation systems with the aid of the Autodesk Flow numerical model. Virtual wind tunnel results revealed that adopting 50% porosity led to the optimum wind reduction (≈75%), no turbulence area, and maximum sheltered area with no sand accumulation over the fences. The final design adopted was a composite made of artificial fences, green-belt trees, and gravel-stabilized areas, accompanied by removing the street barriers, achieving the aerodynamics concept to provide a long-term sustainable solution for the sand encroachment in those areas.

Promoting self‐facilitating feedback processes in coastal ecosystem engineers to increase restoration success: Testing engineering measures

Abstract Coastal ecosystem engineers often depend on self‐facilitating feedbacks to ameliorate environmental stress. This makes the restoration of such coastal ecosystem engineers difficult. We question if we can increase transplantation success in highly dynamic coastal areas by engineering measures that promote the development of self‐facilitating feedback processes. Intertidal blue mussels Mytilus edulis are a typical example of ecosystem engineers that are difficult to restore. A lack of self‐facilitating feedbacks at low densities limits establishment success when young mussels are transplanted on dynamic mudflats. In a large field experiment, we investigated the possibility of increasing transplantation success by stimulating the formation of an aggregated spatial configuration in mussels, thereby reducing hydrologically induced dislodgment and the risks of predation. For this, we applied engineering measures in the form of fences that trapped wave dislodged mussels. Mussel loss rates were significantly lower when mussels were placed between both artificial fences, and in high densities (4.2 kg/m2) compared with mussels placed in areas without fences and in low densities (2.1 kg/m2). The fences induced the formation of a banded pattern with high local mussel densities, which locally reduced predation. Synthesis and applications. Our results underline the importance of actively promoting the development of self‐facilitating processes, such as aggregation into patterns, in restoration projects of ecosystem engineers. In particular, the current study shows that engineering measures can help to initiate these kinds of self‐facilitating interactions, especially in highly dynamic areas.

Effect of live fences of Gliricidia sepium on CO2 fluxes in tropical livestock systems

AbstractLive fences have the potential to improve microclimatic conditions, moderate soil CO2 fluxes and function as carbon sinks. We quantified variation in soil CO2 fluxes from livestock silvopastoral systems under the canopies of live fences (LF), formed by Gliricidia sepium trees, or artificial fences (AF). We determined the responses of soil CO2 fluxes to environmental factors, including diurnal and seasonal variations in temperature and relative humidity in each fencing system. Measurements were made from April to June (dry season) and from July to September (rainy season), 2012. Fluxes were similar between the two livestock systems; LF emitted 1.00 μmol CO2/m2/s and AF 1.02 μmol CO2/m2/s. Soil temperatures at 5 cm depth were 3% warmer in AF than in LF, and relative humidity was 16% greater in LF than in AF. Seasonal variation in temperature greatly affected soil CO2 fluxes, which changed seasonally in parallel with temperature of the topsoil and relative humidity at 1 m height, peaking in late summer. Fluxes in LF and AF were greater in the rainy season (1.1 μmol CO2/m2/s, for both systems), when soil temperature was cooler and relative humidity was greatest, than during the dry season (0.9 μmol CO2/m2/s, for both systems). Soil fluxes were larger at night (00:00–06:00 h), when soil temperature was cooler and relative humidity greater, than during the morning (6:00–12:00 h), when soil temperature was warmer and relative humidity was less. The presence of G. sepium trees in LF did not influence soil CO2 fluxes.

Comparative Study on the Design and Landscape of Egyptian and Saudi Gardens

This study aimed to compare the design and landscape of Egyptian and Saudi gardens to provide information about similarities and differences, and evaluate them for improvement. Two representative gardens were investigated in each country. The Egyptian gardens were Al-Kawsar and Garaman at Sohag Governorate, and the Saudi ones were Al-Escan and King Khalid at Qassim region. All characteristics related to the landscape design and landscape gardening were measured to achieve this study. The results showed many similarities and differences among the Egyptian and Saudi gardens. Both regions had gardens of geometric or natural design but the natural one was incomplete or mixed. All gardens were isolated by mostly artificial fences surrounded by trees or hedges with one principal entry. The routes were artificial, similar in width, regular or irregular, with borders in most cases. However, the Egyptian gardens had different areas, lower routes percentage and hedges on both sides of routes. They also included more divisions, buildings, services and entertainment places compared to Saudi gardens. The sitting places were limited by seats in some locations of the Egyptian gardens versus free sitting on grass in Saudi gardens. The surface irrigation was the system followed in the Egyptian gardens compared to spray irrigation system in the Saudi gardens. Plant distribution was similar in both countries where plants were cultivated around fences or routes with few irregularly cultivated plants as samples on green areas. The formation of plants were applied in all gardens whatever their deign style. There were no flowering beds in most studied gardens but number of flowering plants distributed at random around the routes. However, the Egyptian gardens had lower green areas and higher density and variability in cultivated plants compared to the Saudi gardens. Therefore, the increment of divisions, services and entertainment places, and the enrichment of the density and variability of cultivated plants seemed to be essential in Saudi gardens. The increment of green areas and the application of more economic irrigation system is highly needed in the Egyptian gardens. The improvement of the natural design, to meet the standard criteria, and the cultivation of flowering plants are also recommended in both studied regions. The study provided information about the design and landscape of gardens in two important counties, which may be useful for further improvements.

Prevalence and Species Composition of Live Fences in Village Homegardens A Study in the Low Country Wet Zone of Sri Lanka

Live fences are abundant green infrastructure in farmlands and homegardens. This practice however, is declining due to drivers of urbanisation. The aims of this study were to identify different types of live fences and to evaluate their patterns of prevalence in homegardens in a conventionally agricultural, but rapidly urbanising area of Sri Lanka. The study was conducted during 2014 in 80 homegardens randomly selected from Divulapitiya D.S. division of Gampaha district, located in the low-country wet zone. Smallholder coconut is the main agricultural activity of the area. Data on vegetation types, species composition, land extent, length of fences, and information on local knowledge systems on live fences were collected using a structured survey schedule. Thirty dominant plant species were found in live fences in the area. Sudu Koppa (Polyscia balfouriana, Gliricidia (Gliricidia sepium), and shoe flower (Hibiscus rosa-sinensis) respectively accounts for 19 %, 15 % and 9% of all trees in live fences. 60%of plant population generated benefits only as ornamental foliage while 24%, and 15% of it respectively are multi-purpose trees and flower plants. About a half of respondents indicated that the low cost of establishment as the main reason for selecting live fences. Respondents believed that benefits of live fences cannot be valued solely by monetary terms. 70% of respondents identified need for continuous pruning as the main problem in managing a live fence. Majority of households were willing to replace live fences with other artificial fences or boundary structures if, needed and the capital investments were not constrained. Enhancing the knowledge of global benefits and interventions to increase and integrate potential benefits to the rural economy will contribute to abate the trend of declining practice of live fences and sustain this age-old sustainable environmental friendly practice. Keywords: Ornamental hedges, Species composition, Multi-purpose trees, Urbanisation, Green infrastructure, Gampaha district

INVESTIGATION OF WINDBREAK SYSTEMS TO CONTROL DUST GENERATION AND DISPERSION IN A RECLAIMED LAND: A NUMERICAL APPROACH

INVESTIGATION OF WINDBREAK SYSTEMS TO CONTROL DUST GENERATION AND DISPERSION IN A RECLAIMED LAND: A NUMERICAL APPROACH

Moving On Out: Black Pioneering in Chicago, 1915-1950

In the first half of the twentieth century, many African Americans placed their hopes in property ownership and upward mobility to legitimize black claims to full citizenship. However, “black pioneers” were caught between a hostile white world and the deteriorating conditions in the overcrowded ghetto. While this story is usually told from the vantage point of whites who reacted to such “invasions” with hostility and flight, I center the experiences of black pioneers who were agents of spatial and socioeconomic expansion as well as instigators of integration. Despite the legal and extralegal barriers erected to keep African Americans in the ghetto, black pioneers consistently demonstrated that they would not be contained by these artificial fences. Most often pioneers were from the black middle class, as these men and women had the means and the business connections to purchase homes in white areas.

Relationship between shelterbelt structure and mean wind reduction

Optical porosity is the important structural feature of two-dimensional (2-D) artificial fences and narrow shelterbelts, but not for 3-D, or wide shelterbelts. To determine the important features of wide shelterbelts, we measured the mean wind speed around eight natural shelterbelts of various widths W and total area densities Ad. Our results show that the product of W and Ad, but not W or Ad alone, is useful for predicting the wind sheltering around fully 3-D shelterbelts. There was a strong negative correlation ( p < 0.01) between W × Ad and the minimum relative wind speed. Also, the shelter distance generally increased with increasing W × Ad.

Canopy flow and aspects of the response of plants protected by herbaceous shelterbelts and wood fences

Field experiments have been conducted in the semiarid southwest region of La Pampa, Argentina, in order to investigate the effect of different types of windbreak on wind characteristics and growth parameters of wheat ( Triticum aestivum, Buck Charrua variety) within the sheltered region. Windbreaks decrease wind speed, reducing damage to the crop and improving yield and quality. Sheltering may improve microclimate conditions for plant growth and protects the soil from wind erosion. Aspects of the sheltering ability of four different windbreaks have been tested: single and double row herbaceous ( Tritio secale) shelterbelts, and two different artificial wooden fences, with the same overall average porosity, but with different porosity distributions. Mean velocity, turbulence intensity, skewness distributions and spectral and wavelet analysis have been performed in order to characterise the turbulent flow downstream of the different windbreaks. Wheat grain yield and harvest index were compared with adjacent unsheltered plantations. The single and double row shelterbelts enhanced the grain yield and the harvest index of the protected plants. An influence of the turbulent structure on plant growth is suggested by the different response of plants sheltered by the two types of artificial fences.

Beach protection and restoration Part II: a perspective of “soft” methods

In Part I (Vide previous issue) the authors underscored the world‐wide character of coastal erosion and particularly the shrinking of beaches. If nature is the causal agent, man clearly enhances the process. To counter the steady encroachment of the sea upon the land, several protective devices have been placed along the shores. Some of these were even conceived as means to bring about sand accretion in specific sites. The results have been overall disappointing, or of local value only. In this paper beach protection and beach restoration methods that call upon the natural processes are examined. The “soft” approach to the problem includes implanting artificial reefs, placing vegetation, or fences, on dune or beach, and especially artificial beach nourishment.