Algorithms for data-gathering in wireless sensor networks

Wireless sensor networks consist of a large number of small battery powered sensor nodes with limited energy resources which are responsible for sensing, processing, and transmitting the monitored data. Once deployed, the sensor nodes are normally inaccessible to the user, and thus replacement of the battery is generally not feasible. A major concern in designing and operating dense Wireless Sensor Networks (WSNs) is the energy-efficiency. Hierarchical clustering and cross-layer optimization are widely accepted as effective techniques to ameliorate this concern. We propose two different novel energy efficient algorithms to gather data from sensor nodes. Energy-Efficient Media Access Control (EE-MAC) protocol is the first algorithm, which has excellent scalability and performs well for both small and large sensor networks. We will also provide a theoretical analysis of the protocol and give guidelines on how to find the optimal protocol parameters such as the number of clusters. In addition, we develop and analyze a novel and scalable Spiraled Algorithm for Data-gathering (SAD) that periodically selects cluster heads according to their geographic locations and residual energy by sorting nodes on virtual spirals. Theoretical analysis and simulation results show that SAD can achieve as much as a factor of three prolonging network lifetime compared with other conventional protocols like LEACH especially when the network is large. Moreover, SAD is also able to distribute energy dissipation evenly throughout the sensors such that 80% of the nodes run out of batteries in the last 20% of the network lifetime

Spatial Variation of Surface Residual Stress in Metallic Materials

Shot peening is commonly used to reduce fatigue failures in industrial parts by introducing compressive residual stress into the surface of a material. However, it is challenging to assess the performance of the parts without destroying them. Solving this problem requires a combined model that predicts both recrystallization and residual stress using experimental measurements and predictive computational modelling. Experiments were performed to prove that the surface properties of materials after thermal treatments can be accessed, and the spatial variation of residual stress in metallic materials, including the relationship between surface and subsurface behavior can be evaluated. This process involves investigating the surface residual stress profile using a spatially sensitive X-ray diffraction technique, followed by other procedures such as cutting and investigation of microstructure and subsurface residual stress. With a model like this, the performance of industrial parts can be assessed in a non-destructive way. It is crucial that the parts can still serve the original purpose after being tested

How big should your nanoindentation be? The implications of indentation size in assessing the properties of complex structure

Drivers for testing small volumes of materials for assessing the mechanical properties are either (1) the sample you want to test is very small in the first place, such as measuring the hardness of a wear resistant coating which is in thin film form or (2) you can well-characterize a small volume or the small volume has some spatially distinct feature, such as probing properties near a grain boundary, or in two phase systems. Small scale mechanical testing using instrumented indentation generally requires minimal sample preparation and has high spatial fidelity, but creates complex loading states as opposed to uniaxial or biaxial applied stress methods. However, the ease of use and wide range of samples which are amenable for indentation testing has made this a common tool both for experimental assessment studies and for experimental validation of providing comparisons to simulations and predictions of mechanical properties. Please click Additional Files below to see the full abstract

The Influence of Chemical, Organic and Biological Fertilizers on Agrobiological and Antioxidant Properties of Syrian Cephalaria (Cephalaria Syriaca L.)

Since chemical fertilizers pollute soil, water and crops, conscientious agricultural producers seek alternatives to chemical fertilizers. Biological fertilizers are considered a reliable alternative for improving soil productivity and plant growth in sustainable agriculture. The response of some agrobiological and antioxidant properties of Syrian cephalaria (Cephalaria syriaca L.) to different fertilizer sources was explored in an experiment which included: (i) mycorrhiza + manure; (ii) mycorrhiza + vermicompost; (iii) mycorrhiza + Azotobacter; (iv) mycorrhiza + chemical fertilizer; (v) mycorrhiza; and (vi) control. The results showed that the highest seed yield, biological yield, oil percentage yield, were observed in plants treated with mycorrhiza + vermicompost, whereas the highest 1000-seed weight was obtained from the application of mycorrhiza + manure. With respect to photosynthesizing pigments, the application of mycorrhiza + vermicompost increased chlorophyll a, chlorophyll b, total chlorophyll, carotenoid content as well as total phenols, total flavonoids and DPPH antioxidant activity as compared to control (unfertilized) plants. The mixed application of different fertilizer sources influenced the uptake of trace elements (Fe, Zn and Cu) optimally. In the light of the obtained results for the agrobiological and antioxidant properties of Syrian cephalaria, in most of the measured traits, there is no significant difference between manure, vermicompost and chemical fertilizers in combination with mycorrhiza. Hence the use of organic and biological inputs instead of chemical fertilizer for improving crop efficiency and quality with the aim of alleviating pollution and accomplishing sustainable agriculture is highly encouraging

In vitro comparison of apical microleakage following canal obturation with lateral and thermoplasticized gutta-percha compaction techniques

The purpose of this study was to compare apical microleakage following canal obturation with lateral and thermoplasticized gutta-percha compaction techniques. Ninety extracted single-rooted maxillary teeth were used in this study. Seventy teeth were randomly divided into two groups: One group was obturated by lateral compaction technique and the other was obturated by Obtura II (thermoplasticized gutta-percha compaction technique); 5 teeth were positive controls (without obturation) and 5 teeth were negative controls (with obturation) in each group. The specimens were placed in India ink for 48 h and then divided into two halves. The amount of dye penetration was observed under a stereomicroscope at ×16 magnification and 0.1 mm accuracy. In this study, there was apical leakage in the two experimental groups but the amount of microleakage was not significant. According to the results of independent samples test, there was no significant difference between the two experimental groups.Key words: Apical seal, gutta-percha, lateral compaction, microleakage, Obtura II

Bio-chemical fertilizer improves the oil yield, fatty acid compositions, and macro-nutrient contents in Nigella sativa L.

The present study evaluated the effects of biofertilizers on qualitative and quantitative traits of Nigella sativa L. The experiment was conducted based on a randomized complete block design with 10 treatments and three replications. The treatments included control (no fertilization), U (100% chemical fertilizer as urea at 53.3 kg ha−1, Nb (Biofertilizer, Azotobacter vinelandii), Pb (Biofertilizer, Pantoea agglomerans and Pseudomonas putida), Kb (Biofertilizer, Bacillus spp.), NPKb (NPK combined biofertilizers), Nb + 50% U, Pb + 50% U, Kb + 50% U, and NPKb + 50% U. The highest oil percentage was 46.33 percent related to NPK(b) + U50%, and the highest oil yield was 466.43 kg/ha related to NPK(b) + U50%. The highest seed yield (1006.64 kg/ha) was observed in the plants treated with NPK(b) + U50%. The treatment of K(b) + U50% increased myristic acid by 0.35%. The NPK(b) + U50% treatment reduced palmitic, stearic, and linolenic acid by 11.3, 2.01, and 0.31%, respectively. The highest oleic acid (27.85%) and linoleic acid (56.6%) were obtained from the treatment of NPK(b) + U50%, respectively. The plants treated with NPK(b) + U50% showed the highest seed N percentage (%), P content (mg g−1) and K content (mg g−1 ). In general, NPK(b) + U50% is the best treatment in line with sustainable agriculture