Geographical Information System Approach for Regional Biogas Potential Assessment

The economic prosperity and quality of life in a region are closely linked to the level of its per capita energy consumption. In India more than 70% of the total population inhabits rural areas and 85-90% of energy requirement is being met by bioresources. With dwindling resources, attention of planners is diverted to viable energy alternatives to meet the rural energy demand. Biogas as fuel is one such alternative, which can be obtained by anaerobic digestion of animal residues and domestic and farm wastes, abundantly available in the countryside. Study presents the techniques to assess biogas potential spatially using GIS in Kolar district, Karnataka State, India. This would help decision makers in selecting villages for implementing biogas programmes based on resource availability. Analyses reveal that the domestic energy requirement of more than 60% population can be met by biogas option. This is based on the estimation of the per capita requirement of gas for domestic purposes and availability of livestock residues.

A multifold reduction in the transition Reynolds number, and ultra-fast mixing, in a micro-channel due to a dynamical instability induced by a soft wall

A dynamical instability is observed in experimental studies on micro-channels of rectangular cross-section with smallest dimension 100 and 160 mu m in which one of the walls is made of soft gel. There is a spontaneous transition from an ordered, laminar flow to a chaotic and highly mixed flow state when the Reynolds number increases beyond a critical value. The critical Reynolds number, which decreases as the elasticity modulus of the soft wall is reduced, is as low as 200 for the softest wall used here (in contrast to 1200 for a rigid-walled channel) The instability onset is observed by the breakup of a dye-stream introduced in the centre of the micro-channel, as well as the onset of wall oscillations due to laser scattering from fluorescent beads embedded in the wall of the channel. The mixing time across a channel of width 1.5 mm, measured by dye-stream and outlet conductance experiments, is smaller by a factor of 10(5) than that for a laminar flow. The increased mixing rate comes at very little cost, because the pressure drop (energy requirement to drive the flow) increases continuously and modestly at transition. The deformed shape is reconstructed numerically, and computational fluid dynamics (CFD) simulations are carried out to obtain the pressure gradient and the velocity fields for different flow rates. The pressure difference across the channel predicted by simulations is in agreement with the experiments (within experimental errors) for flow rates where the dye stream is laminar, but the experimental pressure difference is higher than the simulation prediction after dye-stream breakup. A linear stability analysis is carried out using the parallel-flow approximation, in which the wall is modelled as a neo-Hookean elastic solid, and the simulation results for the mean velocity and pressure gradient from the CFD simulations are used as inputs. The stability analysis accurately predicts the Reynolds number (based on flow rate) at which an instability is observed in the dye stream, and it also predicts that the instability first takes place at the downstream converging section of the channel, and not at the upstream diverging section. The stability analysis also indicates that the destabilization is due to the modification of the flow and the local pressure gradient due to the wall deformation; if we assume a parabolic velocity profile with the pressure gradient given by the plane Poiseuille law, the flow is always found to be stable.

El vehículo eléctrico en el ámbito de las microrredes eléctricas.

[ES]En este trabajo se propone el diseño técnico de una microrred eléctrica para la recarga domestica del vehículo eléctrico a partir de energías renovables. Para ello se realizará un estudio del emplazamiento de la instalación y con los datos obtenidos se decidirá la fuente de generación renovable más adecuada para satisfacer el requerimiento de energía para la recarga. A continuación se elegirán los componentes que completen la instalación.

All-optical OFDM and distributed Raman amplification: Challenges to enable high capacities and extend reach

We review recent advances in all-optical OFDM technologies and discuss the performance of a field trial of a 2 Tbit/s Coherent WDM over 124 km with distributed Raman amplification. The results indicate that careful optimisation of the Raman pumps is essential. We also consider how all-optical OFDM systems perform favourably against energy consumption when compared with alternative coherent detection schemes. We argue that, in an energy constrained high-capacity transmission system, direct detected all-optical OFDM with 'ideal' Raman amplification is an attractive candidate for metro area datacentre interconnects with ~100 km fibre spans, with an overall energy requirement at least three times lower than coherent detection techniques.

On efficient data integrity and data origin authentication for wireless sensor networks utilising block cipher design techniques

Analysis of the generic attacks and countermeasures for block cipher based message authentication code algorithms (MAC) in sensor applications is undertaken; the conclusions are used in the design of two new MAC constructs Quicker Block Chaining MAC1 (QBC-MAC1) and Quicker Block Chaining MAC2 (QBC-MAC2). Using software simulation we show that our new constructs point to improvements in usage of CPU instruction clock cycle and energy requirement when benchmarked against the de facto Cipher Block Chaining MAC (CBC-MAC) based construct used in the TinySec security protocol for wireless sensor networks.

The Nematode-Copepod Ratio And Its Use In Pollution Ecology

The nematode/copepod ratio is critically examined with a view to adding some precision to its proposed use in pollution ecology. At two unpolluted intertidal sites, differing markedly in sediment grade, the metabolic requirements of copepods are shown to be equivalent to the requirements of that fraction of the nematode population which feeds in the same way. The partitioning of this total energy requirement among individuals depends on the distribution of individual metabolic body sizes and the relative rates of metabolism. The distribution of body sizes is constrained by the sediment granulometry, which affects nematodes and copepods differently. These considerations enable precise predictions of the nematode/copepod ratios expected in unpolluted situations, against which observed ratios can be compared.

Effect of high temperature, biaxial stretching on the thermal and mechanical properties of HDPE/MWCNT sheet

High density polyethylene (HDPE)/multi-walled carbon nanotube (MWCNT) composites containing 4 wt% MWCNTs were prepared by melt mixing followed by compression moulding into sheet. Compression moulded sheets were heated to just below the melting temperature and biaxially stretched at ratios (SRs) of 2, 2.5 and 3.0. The effect of stretching on the thermal and mechanical properties of the sheet was studied by differential scanning calorimetry (DSC) and tensile testing. DSC results show that the crystallinity of all the stretched samples increases by approximately 13% due to strain induced crystallization. The melting temperature of the biaxially stretched samples increases only slightly while crystallization temperature is not affected. Tensile test results indicate that at a SR of 2.5 the elastic modulus of the stretched composites increases by 17.6% relative to the virgin HDPE, but the breaking strength decreases by 33%. While the elastic modulus and breaking strength of the HDPE/MWCNT samples continue to increase as SR increases they drop off after a SR of 2.5 for the virgin HDPE. This is probably due to the constraining influence of the nanotubes preventing the relaxation of polymer chains caused by adiabatic heating at high SRs. The addition of MWCNTs results in significant strain hardening during deformation. While this will lead to increased energy requirement in forming it will also result in a more stable process and the ability to produce deep draw containers with more uniform wall thickness

A comparative evaluation of functions for the analysis of growth in male broilers

Data from six studies with male broilers fed diets covering a wide range of energy and protein were used in the current two analyses. In the first analysis, five models, specifically re-parameterized for analysing energy balance data, were evaluated for their ability to determine metabolizable energy intake at maintenance and efficiency of utilization of metabolizable energy intake for producing gain. In addition to the straight line, two types of functional form were used. They were forms describing (i) diminishing returns behaviour (monomolecular and rectangular hyperbola) and (ii) sigmoidal behaviour with a fixed point of inflection (Gompertz and logistic). These models determined metabolizable energy requirement for maintenance to be in the range 437-573 kJ/kg of body weight/day depending on the model. The values determined for average net energy requirement for body weight gain varied from 7(.)9 to 11(.)2 kJ/g of body weight. These values show good agreement with previous studies. In the second analysis, three types of function were assessed as candidates for describing the relationship between body weight and cumulative metabolizable energy intake. The functions used were: (a) monomolecular (diminishing returns behaviour), (b) Gompertz (smooth sigmoidal behaviour with a fixed point of inflection) and (c) Lopez, France and Richards (diminishing returns and sigmoidal behaviour with a variable point of inflection). The results of this analysis demonstrated that equations capable of mimicking the law of diminishing returns describe accurately the relationship between body weight and cumulative metabolizable energy intake in broilers.

Evaluation of a PVT Air Collector

Hybrid Photovoltaic Thermal (PVT) collectors are an emerging technology that combines PV and solar thermal systems in a single solar collector producing heat and electricity simultaneously. The focus of this thesis work is to evaluate the performance of unglazed open loop PVT air system integrated on a garage roof in Borlänge. As it is thought to have a significant potential for preheating ventilation of the building and improving the PV modules electrical efficiency. The performance evaluation is important to optimize the cooling strategy of the collector in order to enhance its electrical efficiency and maximize the production of thermal energy. The evaluation process involves monitoring the electrical and thermal energies for a certain period of time and investigating the cooling effect on the performance through controlling the air mass flow provided by a variable speed fan connected to the collector by an air distribution duct. The distribution duct transfers the heated outlet air from the collector to inside the building. The PVT air collector consists of 34 Solibro CIGS type PV modules (115 Wp for each module) which are roof integrated and have replaced the traditional roof material. The collector is oriented toward the south-west with a tilt of 29 ᵒ. The collector consists of 17 parallel air ducts formed between the PV modules and the insulated roof surface. Each air duct has a depth of 0.05 m, length of 2.38 m and width of 2.38 m. The air ducts are connected to each other through holes. The monitoring system is based on using T-type thermocouples to measure the relevant temperatures, air sensor to measure the air mass flow. These parameters are needed to calculate the thermal energy. The monitoring system contains also voltage dividers to measure the PV modules voltage and shunt resistance to measure the PV current, and AC energy meters which are needed to calculate the produced electrical energy. All signals recorded from the thermocouples, voltage dividers and shunt resistances are connected to data loggers. The strategy of cooling in this work was based on switching the fan on, only when the difference between the air duct temperature (under the middle of top of PV column) and the room temperature becomes higher than 5 °C. This strategy was effective in term of avoiding high electrical consumption by the fan, and it is recommended for further development. The temperature difference of 5 °C is the minimum value to compensate the heat losses in the collecting duct and distribution duct. The PVT air collector has an area of (Ac=32 m2), and air mass flow of 0.002 kg/s m2. The nominal output power of the collector is 4 kWppv (34 CIGS modules with 115 Wppvfor each module). The collector produces thermal output energy of 6.88 kWth/day (0.21 kWth/m2 day) and an electrical output energy of 13.46 kWhel/day (0.42 kWhel/m2 day) with cooling case. The PVT air collector has a daily thermal energy yield of 1.72 kWhth/kWppv, and a daily PV electrical energy yield of 3.36 kWhel /kWppv. The fan energy requirement in this case was 0.18 kWh/day which is very small compared to the electrical energy generated by the PV collector. The obtained thermal efficiency was 8 % which is small compared to the results reported in literature for PVT air collectors. The small thermal efficiency was due to small operating air mass flow. Therefore, the study suggests increasing the air mass flow by a factor of 25. The electrical efficiency was fluctuating around 14 %, which is higher than the theoretical efficiency of the PV modules, and this discrepancy was due to the poor method of recording the solar irradiance in the location. Due to shading effect, it was better to use more than one pyranometer.

Nutrient intake and plate waste from an Australian residential care facility

Objective: To determine the plate waste, energy and selected-nutrient intake, from elderly residents living in a high-level care (HLC) and low-level care (LLC) facility.

Design: Three, single, whole day assessments of plate waste, energy, and selected nutrients, using a visual rating plate waste scale.

Setting: Long-term residential care establishment.

Subjects: One hundred and sixty-nine (93 HLC and 76 LLC) individual daily intakes.

Main findings: The mean energy wasted throughout the whole day was 17%. The energy wasted from main meals (16%) was significantly less than the energy wasted at mid-meals (22%, P=0.049). The lowest mean energy wastage occurred at breakfast (8%) compared to lunch (22%) and dinner (25%, P<0.001). The mean (s.d.) daily energy served and consumed was 8.1 (2.0) and 6.6 (2.2) MJ, respectively. There was no difference in energy served or consumed between HLC and LLC residents. On the observation day, 60% of residents consumed less than their estimated energy requirement. The mean calcium intake was 796 (346) mg, and the median (inter-quartile range) vitamin D intake was 1.78 (2.05) μg.

Conclusion: On 1 day, more than half the residents surveyed were at risk of consuming an inadequate energy intake, which over-time, may result in body weight loss. Although wastage was not excessive and energy served was adequate, the amount of food eaten was insufficient to meet energy and calcium requirements for a significant number of residents and it is not possible to consume sufficient vitamin D through food sources.

Size matters : extraordinary rodent abundance on an Australian tropical floodplain

Published estimates of the total biomass of natural populations of mammalian herbivores generally have ignored small-bodied taxa (especially, rodents). Including such taxa may dramatically change our understanding of total biomass and energy flow in such systems. Dusky rats (Rattus colletti) are small (up to 210 g) native Australian mammals, and our 5-year mark-recapture study on a tropical flood plain (Adelaide River, Northern Territory) revealed that rat biomass can reach extraordinary levels (up to 4.7 t km⁻²). Because their small body size results in high mass-specific metabolic rates, a given biomass of rodents has a several-fold higher total energy requirement than the same mass of large-bodied herbivores. Accordingly, during some years dusky rat biomass can be double that estimated for large herbivores on the world's most productive savannas in eastern and southern Africa. The huge rodent biomass strongly suggests that the Adelaide River flood plain must be an incredibly productive habitat. Considering the immense biological importance of these productive ecosystems, flood plain conservation must be placed high on the priority list of habitats that require immediate protection.

Estimating the contribution of carnivorous waterbirds to nutrient loading in freshwater habitats

1. We estimated nitrogen (N) and phosphorus (P) loading into wetlands by carnivorous waterbirds with alternative physiological models using a food-intake and an excreta-production approach. The models were applied for non-breeding and breeding Dutch inland carnivorous waterbird populations to quantify their contribution to nutrient loading on a landscape scale.

2. Model predictions based on food intake exceeded those based on excretion by 59–62% for N and by 2–36% for P, depending on dietary assumptions. Uncertainty analysis indicated that the intake model was most affected by errors in energy requirement, while the excretion model was dependent on faecal nutrient composition.

3. Per capita loading rate of non-breeders increased with body mass from 0.3–0.8 g N day⁻¹ and 0.15 g P day⁻¹ in little gulls Larus minutus to 4.5–11.5 g N day⁻¹ and 2.1–3.2 g P day⁻¹ in great cormorants Phalacrocorax carbo. For breeding birds, the estimated nutrient loading by a family unit over the entire breeding period ranged between 17.6–443.0 g N and 8.6 g P for little tern Sterna albifrons to 619.6–1755.6 g N and 316.2–498.1 g P for great cormorants.

4. We distinguished between external (i.e. importing) and internal (i.e. recycling) nutrient loading by carnivorous waterbirds. For the Netherlands, average external-loading estimates ranged between 38.1–91.5 tonnes N and 16.7–18.2 tonnes P per year, whilst internal-loading estimates ranged between 53.1–140.5 tonnes N and 25.2–39.2 tonnes P and per year. The average contribution of breeding birds was estimated to be 17% and 32% for external and internal loading respectively. Most important species were black-headed gull Larus ridibundus and mew gull Larus canus for external loading, and great cormorant and grey heron Ardea cinerea for internal loading.

5. On a landscape scale, loading by carnivorous waterbirds was of minor importance for freshwater habitats in the Netherlands with 0.26–0.65 kg N ha⁻¹ a⁻¹ and 0.12–0.16 kg P ha⁻¹ a⁻¹. However, on a local scale, breeding colonies may be responsible for significant P loading.

Towards healthy and sustainable food consumption: an Australian case study

Objective To articulate a healthy and sustainable (H&S) diet; outline key health and environmental sustainability principles that can be applied in the selection of foods for inclusion in such a diet; and describe a methodology with which to assess the availability and affordability of a H&S food basket.

Design We synthesized publically available evidence on the environmental impact of different foods from academic, government, industry and non-government sources and constructed a hypothetical H&S equivalent of the typical Australian diet. Based on this, we constructed a weekly H&S food basket for a household of two adults and two children.

Setting Australia.

Subjects Australian populations.

Results The H&S diet is based on three overarching principles: (i) any food that is consumed above a person's energy requirement represents an avoidable environmental burden in the form of greenhouse gas emissions, use of natural resources and pressure on biodiversity; (ii) reducing the consumption of discretionary food choices, which are energy-dense and highly processed and packaged, reduces both the risk of dietary imbalances and the use of environmental resources; and (iii) a diet comprising less animal- and more plant-derived foods delivers both health and ecological benefits.

Conclusions We have focused on the articulation of a H&S diet not to facilitate ‘policy drift’ to focus on individual dietary choice, but rather to provide evidence to extend dietary guideline recommendations so as to integrate environmental considerations within the scope of food and health policy advice in Australia and elsewhere.

Hoarding of pulsed resources : temporal variations in egg-caching by arctic fox

Resource pulses are common in various ecosystems and often have large impacts on ecosystem functioning. Many animals hoard food during resource pulses, yet how this behaviour affects pulse diffusion through trophic levels is poorly known because of a lack of individual-based studies. Our objective was to examine how the hoarding behaviour of arctic foxes (Alopex lagopus) preying on a seasonal pulsed resource (goose eggs) was affected by annual and seasonal changes in resource availability. We monitored foraging behaviour of foxes in a greater snow goose (Chen caerulescens atlanticus) colony during 8 nesting seasons that covered 2 lemming cycles. The number of goose eggs taken and cached per hour by foxes declined 6-fold from laying to hatching, while the proportion of eggs cached remained constant. In contrast, the proportion of eggs cached by foxes fluctuated in response to the annual lemming cycle independently of the seasonal pulse of goose eggs. Foxes cached the majority of eggs taken (> 90%) when lemming abundance was high or moderate but only 40% during the low phase of the cycle. This likely occurred because foxes consumed a greater proportion of goose eggs to fulfill their energy requirement at low lemming abundance. Our study clearly illustrates a behavioural mechanism that extends the energetic benefits of a resource pulse. The hoarding behaviour of the main predator enhances the allochthonous nutrients input brought by migrating birds from the south into the arctic terrestrial ecosystem. This could increase average predator density and promote indirect interactions among prey.

Effects of different nutritional regimens on the productivity of Australian Cashmere goats and the partitioning of nutrients between cashmere and hair growth

The influence of energy or protein supplementation or energy restriction on cashmere growth was studied in 35 highly productive cashmere wether goats. The goats were shorn on 3 December and randomly allocated to 3 levels of energy intake: M, goats fed to maintain liveweight; 0.8M, goats fed to lose 5 kg liveweight from December to April and then fed ad libitum; and >M, goats fed to gain liveweight. Nested within >M were ADLIB (goats offered feed ad libitum), and 1.25M and l.5M (goats fed M plus 25 or 50% of the difference in mean intake between M and ADLIB). The metabolisable energy requirement to maintain liveweight was 250 kJ kg-0.75 day-1 but to maintain body condition (l.25M) it was 3 12 kJ kg-0.75 day-1. Goats fed 0.8M had a mean intake of 0.68M and lost 26 g day-1 liveweight until April, but when fed ad libitum consumed 2.15M in June and grew rapidly in late autumn and winter at 93 g day-1. Goats fed ADLIB consumed 2.30M in February and gained 87 g day-1 from December to February, but intake declined to 1.61 M in June and they gained 20 g day-1 from April to June. Cashmere growth and fibre diameters of fleeces shorn on 17 June of goats fed >M (221g, 17.69 pm) were significantly greater (P< 0.02) than those of goats fed 0.8M (146 g, 16.67 ¦m), with levels of M-fed goats being intermediate. Within >M, there were no significant differences in cashmere growth. Protein supplementation within M (27 or 54 g day -1 formaldehyde- treated casein) resulted in 40% more wool growth in sheep (P<0.001), but no increase in cashmere or hair growth in goats. Goats fed ADLIB had significantly reduced cashmere yields (P < 0.05) and grew more hair (P<0.05) than did goats in other treatments. About 4 weeks after energy supplementation, fibre diameter of previously energy-deprived goats increased (P< 0.01). Midside patches indicated that energy-deprived goats, which lost liveweight, diverted nutrients preferentially to cashmere growth, while goats fed ADLIB partitioned nutrients towards hair growth. To maximise cashmere growth, supplementary energy should be supplied to avoid liveweight loss from December to April. Goats that had small (1-2 kg) liveweight gains and maintained body condition achieved near maximal levels of cashmere growth.