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Beaconless Position-based Routing with Guaranteed Delivery for Wireless Ad hoc and Sensor Networks

自动化学报 2006年第6期32卷 846-855页

作者： CHAWLA Mohit GOEL Nishith KALAICHELVAN Kalai NAYAK Amiya STOJMENOVIC Ivan Department of Computer Science & Engineering IIT GuwahatiGuwahati 781039India Cistel Technology Inc OttawaOntario K2E 7V7Canada EION Technology Inc OttawaOntario K1Y 2X5Canada SITE University of OttawaOttawaOntario K1N 6N5Canada

Existing position-based routing algorithms, where packets are forwarded in the geographic direction of the destination, normally require that the forwarding node should know the positions of all neighbors in its transmission range. This information on direct neighbors is gained by observing beacon messages that each node sends out periodically. Several beaconless greedy routing schemes have been proposed recently. However, none of the existing beaconless schemes guarantee the delivery of packets. Moreover, they incur communication overhead by sending excessive control messages or by broadcasting data packets. In this paper, we describe how existing localized position based routing schemes that guarantee delivery can be made beaconless, while preserving the same routes. In our guaranteed delivery beaconless routing scheme, the next hop is selected through the use of control RTS/CTS messages and biased timeouts. In greedy mode, the neighbor closest to destination responds first. In recovery mode, nodes closer to the source will select shorter timeouts, so that other neighbors, overhearing CTS packets, can eliminate their own CTS packets if they realize that their link to the source is not part of Gabriel graph. Nodes also cancel their packets after receiving data message sent by source to the selected neighbor. We analyze the behavior of our scheme on our simulation environment assuming ideal MAC, following GOAFR+ and GFG routing schemes. Our results demonstrate low communication overhead in addition to guaranteed delivery.

关键词： Beaconless routing geometric routing guaranteed delivery sensor networks

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Effect of silver in thermal treatments of Fe-Mn-C degradable metals:Implications for stent processing

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Bioactive Materials 2022年第6期7卷 30-41页

作者： Sergio Loffredo Sofia Gambaro Francesco Copes Carlo Paternoster Nicolas Giguere Maurizio Vedani Diego Mantovani Laboratory for Biomaterials and Bioengineering Canada Research Chair I in Biomaterials and Bioengineering for the Innovation in SurgeryDepartment of Min-Met-Materials EngineeringResearch Center of CHU de QuebecDivision of Regenerative MedicineLaval UniversityQuebec CityQC G1V 0A6Canada Department of Mechanical Engineering Politecnico di MilanoMilan20156Italy National research Council Institute of Condensed Matter Chemistry and Technologies for Energy CNR-ICMATEGenoa16149Italy Quebec Metallurgy Center CMQ Trois-RivieresQCG9A 5E1Canada

Twinning-induced plasticity(TWIP)steels are considered excellent materials for manufacturing products requiring extremely high mechanical properties for various applications including thin medical devices,such as biodegradable intravascular *** is also proven that the addition of Ag can guarantee an appropriate degradation while implanted in human body without affecting its bioactive *** order to develop an optimized manufacturing process for thin stents,the effect of Ag on the recrystallization behavior of TWIP steels needs to be *** is of major importance since manufacturing stents involves several intermediate recrystallization annealing *** this work,the recrystallization mechanism of two Fe-Mn-C steels with and without Ag was thoroughly investigated by microstructural and mechanical *** was observed that Ag promoted a finer microstructure with a different texture evolution,while the recrystallization kinetics resulted *** presence of Ag also reduced the effectiveness of the recrystallization *** behavior was attributed to the presence of Ag-rich second phase particles,precipitation of carbides and to the preferential development of grains possessing a{111}orientation upon thermal *** prominence of{111}grains can also give rise to premature twinning,explaining the role of Ag in reducing the ductility of TWIP steels already observed in other ***,in vitro biological performances were unaffected by *** findings could allow the design of efficient treatments for supporting the transformation of Fe-Mn-C steels alloyed with Ag into commercial products.

关键词： Twinning Recrystallization Biomaterials Silver Steels

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Correspondence of bubble size and frother partitioning in flotation

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中南大学学报：英文版 2014年第6期21卷 2383-2390页

作者：张炜 Jan E.Nesset James A.Finch Mining & Mineral Resources Division Department of Business AdministrationChinalco China Copper Corporation Limited Department of Mining and Materials Engineering McGill UniversityMontrealQCH3A 0C5Canada

The size of bubbles created in the flotation process is of great importance to the efficiency of the mineral separation ***,it is believed that frother transport between phases is perhaps the most important reason for the interactive nature of the phenomena occurring in the bulk and froth phases in flotation,as frother adsorbed in the surface of rising bubbles is removed from the bulk phase and then released into the froth as a fraction of the bubbles *** causes the increased concentration in the froth compared to the bulk concentration,named as frother *** reflects the adsorption of frother on bubbles and how to influence bubble size is not *** currently exists no such a topic aiming to link these two key *** fill this vacancy,the correspondence between bubble size and frother partitioning was *** size was measured by sampling-for-imaging(SFI)*** total organic carbon(TOC)analysis to measure the frother partitioning between froth and bulk phases was *** have shown,with no exceptions including four different frothers,higher frother concentration is in the bulk than in the *** results also show strong partitioning giving an increase in bubble size which implies there is a compelling relationship between these two,represented by CFroth/CBulk and *** CFroth/CBulkand D32 curves show similar exponential decay relationships as a function of added frother in the system,strongly suggesting that the frother concentration gradient between the bulk solution and the bubble interface is the driving force contributing to bubble size reduction.

关键词：气泡尺寸浮选过程起泡剂分区体积浓度技术测量曲线显示矿物分离

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Numerical investigation into pillar failure induced by time-dependent skin degradation

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International Journal of Mining Science and Technology 2017年第4期27卷 591-597页

作者： Sainoki Atsushi Mitri Hani S. Department of Mining and Materials Engineering McGill University Montreal H3A0E8 Canada

This paper focuses on the instability mechanism of an isolated pillar, caused by time-dependent skin degradation and strength heterogeneity. The time-dependent skin degradation is simulated with a non-linear rheological model capable of simulating tertiary creep, whereby two different pillar failure cases are investigated. The first case is of an isolated pillar in a deep hard rock underground mine and subjected to high stresses. The results show that pillar degradation is limited to the regions near the surface or the skin until two months after ore extraction. Afterwards degradation starts to extend deeper into the pillar, eventually leaving a highly-stressed pillar core due to stress transfer from the failed *** potential indices show that the risk increases exponentially at the core as time goes by. It is then demonstrated that the progressive skin degradation cannot be simulated with conventional strain-softening model assuming brittle failure. The parametric study with respect to the degree of heterogeneity reveals that heterogeneity is key to the occurrence of progressive skin degradation. The second case investigated in this study is pillar failure taking place in a very long period. Such failure becomes significantly important when assessing the risk for ground subsidence caused by pillar collapse in an abandoned mine. The analysis results demonstrate that the employed non-linear rheological model can simulate gradual skin degradation taking place over several hundred years. The percentage of damage zone volume within the pillar is merely 1% after a lapse of one days and increases to 50% after one hundred years, indicating a high risk for pillar collapse in the long term. The vertical displacements within the pillar also indicate the risk of subsidence. The proposed method is suitable for evaluating the risk of ground surface subsidence above an abandoned mine.

关键词： Pillar stability Underground mine Skin degradation Rheological model Time-dependent failure

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Constitutive analysis of AZ31 magnesium alloy plate

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Journal of Central South University 2010年第1期17卷 7-12页

作者：余琨蔡志勇王晓艳史褆黎文献 School of Materials Science and Engineering Central South University

The plastic deformation simulation of AZ31 magnesium alloy at different elevated temperatures (from 473 to 723 K) was performed on Gleeble-1500 thermal mechanical simulator at the strain rates of 0.01, 0.1, 1, 5 and 10 s-1 and the maximum deformation degree of 80%. The relationship between the flow stress and deformation temperature as well as strain rate was analyzed. The materials parameters and the apparent activation energy were calculated. The constitutive relationship was established with a Zener-Hollomon (Z) parameter. The results show that the flow stress increases with the increase of strain rate at a constant temperature, but it decreases with the increase of deformation temperature at a constant strain rate. The apparent activation energy is estimated to be 129-153 kJ/mol, which is close to that for self-diffusion of magnesium. The established constitutive relationship can reflect the change of flow stress during hot deformation.

关键词：镁合金板 AZ31镁合金表观活化能热模拟实验机温度升高变形模拟流动应力应变速率

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Optimal slot dimension for skirt support structure of coke drums

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Frontiers of Mechanical Engineering 2018年第4期13卷 554-562页

作者： Edward WANG Zihui XIA Department of Mechanical Engineering University of Alberta Edmonton T6G1H9 Canada

The skirt-to-shell junction weld on coke drums is susceptible to fatigue failure due to severe thermal cyclic stresses. One method to decrease junction stress is to add slots near the top of the skirt, thereby reducing the local stiffness close to the weld. The most common skirt slot design is thin relative to its circumferential spacing. A new slot design, which is significantly wider, is proposed. In this study, thermal-mechanical elastoplastic 3-D finite element models of coke drums are created to analyze the effect of different skirt designs on the stress/strain field near the shell-to-skirt junction weld, as well as any other critical stress locations in the overall skirt design. The results confirm that the inclusion of the conventional slot design effectively reduces stress in the junction weld. However, it has also been found that the critical stress location migrates from the shell-to-skirt junction weld to the slot ends. A method is used to estimate the fatigue life near the critical areas of each skirt slot design. It is found that wider skirt slots provide a significant improvement on fatigue life in the weld and slot area.

关键词： coke drum stress analysis cyclic stress fatigue life skirt slots

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Genetic diversity and population structure of Pisum sativum accessions for marker-trait association of lipid content

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The Crop Journal 2015年第3期3卷 238-245页

作者： Sajjad Ahmad Simerjeet Kaur Neil Dylan Lamb-Palmer Mark Lefsrud Jaswinder Singh Department of Plant Science Mc Gill University Ste Anne de Bellevue Quebec H9X 3V9 Canada Department of Bioresource Engineering Mc Gill University Ste Anne de Bellevue Quebec H9X 3V9 Canada

Field pea(Pisum sativum L.) is an important protein-rich pulse crop produced globally. Increasing the lipid content of Pisum seeds through conventional and contemporary molecular breeding tools may bring added value to the crop. However, knowledge about genetic diversity and lipid content in field pea is limited. An understanding of genetic diversity and population structure in diverse germplasm is important and a prerequisite for genetic dissection of complex characteristics and marker-trait associations. Fifty polymorphic microsatellite markers detecting a total of 207 alleles were used to obtain information on genetic diversity, population structure and marker-trait associations. Cluster analysis was performed using UPGMA to construct a dendrogram from a pairwise similarity matrix. Pea genotypes were divided into five major clusters. A model-based population structure analysis divided the pea accessions into four groups. Percentage lipid content in 35 diverse pea accessions was used to find potential associations with the SSR markers. Markers AD73, D21, and AA5 were significantly associated with lipid content using a mixed linear model(MLM) taking population structure(Q) and relative kinship(K) into account. The results of this preliminary study suggested that the population could be used for marker-trait association mapping studies.

关键词： Diversity Field Pea Lipid content Marker-trait association Mixed linear model SSR

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Physicochemical aspects of allanite flotation

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Journal of Rare Earths 2014年第5期32卷 476-486页

作者： Adam Jordens Chris Marion Olga Kuzmina Kristian E.Waters Department of Mining and Materials Engineering McGill University

This paper investigated the physicochemical properties of allanite, a RE-silicate, by measuring zeta potential in the absence and presence of three different flotation collectors （benzohydroxamic acid, sodium oleate and dodecylamine）. This data was then verified by microflotation experiments and with bubble-particle attachment pictures. The investigated properties of allanite were com- pared to those of quartz, a common gangue mineral in many RE deposits. The results of this work indicated that only dodecylamine was able to achieve a selective separation of allanite and quartz. This was accomplished by lowering the dodecylamine dosage so that only quartz was recovered by microflotation.

关键词： allanite flotation surface chemistry zeta potential bubble-particle attachment rare earths

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Flotation behavior and electronic simulations of rare earth minerals in the presence of dolomite supernatant using sodium oleate collector

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Journal of Rare Earths 2019年第1期37卷 101-112,M0005页

作者： E.R.L.Espiritu G.R.da Silva D.Azizi F.Larachi K.E.Waters Department of Mining and Materials Engineering McGill University Department of Chemical Engineering Université Laval

Common rare earth (RE) minerals, such as bastnasite and monazite, may be formed in deposits associated with carbonate gangue, such as calcite and dolomite. Sodium oleate is a widely used collector for the flotation of both RE and gangue minerals, which might, therefore, be an inefficient process due to the lack of selectivity of this collector. Since these minerals are also sparingly soluble in solution, they could release their constituent ions into the solution, which could affect the floatability of other minerals. In this study, the interactions of sodium oleate with bastn(a|¨)site and monazite in the presence of dissolved dolomite species have been investigated. Micro flotation tests were carried out to explore the effects of these dissolved species on the floatability of the RE minerals. Zeta potential measurements and XPS characterization were carried out to understand how the species affect the collector adsorption. To complement these characterizations, density functional theory (DFT) simulations were conducted to investigate the collector-mineral and collector-adsorbed species (on the mineral surface) *** results show that collector-dolomite interaction energy is greater than that of collector-adsorbed species, but lower than collector-monazite interaction energy, explaining the decrease in the minerals’recovery upon exposure to the dissolved mineral species. It is also shown that oleate ions (OI^-) have the strongest interaction with the minerals compared to other oleate species such as acid soap (HOI_2^-) and oleate dimer (Ol_2^(2-)). The behavior (strength and selectivity) of sodium oleate towards RE minerals and dolomite, as compared to other RE mineral collectors (such as aromatic hydroxamate), is attributed mainly to the collector's and the minerals'structure. The long hydrocarbon chain of sodium oleate which imparts hydrophobic characteristic to the minerals, makes it stronger collector than ***, sodium oleate (wit

关键词： Rare earth minerals Bastnasite Monazite Dolomite Sodium oleate DFT simulation

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Quantitative analysis with plastic strain indicators to estimate damage induced by fault-slip

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Journal of Rock Mechanics and Geotechnical Engineering 2018年第1期10卷 1-10页

作者： Atsushi Sainoki Hani S.Mitri International research Organization for Advanced Science and Technology Kumamoto University Department of Mining and Materials Engineering McGill University

In the present study, methodologies to evaluate damage around an underground opening due to seismic waves arising from mining-induced fault-slip are examined. First, expressions for an associated flow rule with a failure criterion are developed for biaxial stress conditions, which are implemented into FLAC3D code. A three-dimensional(3D) mine model encompassing a fault running parallel to a steeply dipping orebody is constructed, whereby static and dynamic analyses are performed to extract stopes and simulate fault-slip in dynamic condition, respectively. In the analysis, the developed biaxial model is applied to the stope wall. The fault-slip simulation is performed, considering shearing of fault surface asperities and resultant stress drop driving the fault-slip. Two methodologies to evaluate damage caused by seismic waves arising from the simulated fault-slip are examined:(i) the ratio of dynamic plastic strain increment to elastic strain limit and(ii) plastic strain energy density. For the former one, two types of strain increments are tested, namely effective shear strain increment and volumetric strain *** results indicate that volumetric strain increment is a suitable index for detecting damage near the stope wall, while effective shear strain increment is appropriate for evaluating damage in backfill. The evaluation method with plastic strain energy density is found to be capable of assessing damage accumulated in an extensive area caused by rock mass oscillation due to seismic wave propagation. Possible damage to mine developments in the proximity of a stope is clearly described with the index. The comparison of the two methods clarifies that the former one assesses "instantaneous" damage, which is found to be different from "accumulated" damage calculated using plastic strain energy density, in terms of damage area and its location. It is thus concluded that the combination of the two methodologies leads to more accurate damage assessment as a pr

关键词： Stability of mine opening Mining-induced fault-slip Seismic waves Biaxial stress condition

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