Compact Routing Research Articles

Certification of Compact Low-Stretch Routing Schemes

On the one hand, the correctness of routing protocols in networks is an issue of utmost importance for guaranteeing the delivery of messages from any source to any target. On the other hand, a large collection of routing schemes have been proposed during the last two decades, with the objective of transmitting messages along short routes, while keeping the routing tables small. Regrettably, all these schemes share the property that an adversary may modify the content of the routing tables with the objective of, e.g., blocking the delivery of messages between some pairs of nodes, without being detected by any node. In this paper, we present a simple certification mechanism which enables the nodes to locally detect any alteration of their routing tables. In particular, we show how to locally verify the stretch-3 routing scheme by Thorup and Zwick [SPAA 2001] by adding certificates of $\widetilde{O}(\sqrt{n})$ bits at each node in $n$-node networks, that is, by keeping the memory size of the same order of magnitude as the original routing tables. We also propose a new name-independent routing scheme using routing tables of size $\widetilde{O}(\sqrt{n})$ bits. This new routing scheme can be locally verified using certificates on $\widetilde{O}(\sqrt{n})$ bits. Its stretch is3 if using handshaking, and 5 otherwise.

Tritium supply and use: a key issue for the development of nuclear fusion energy

Full power operation of the International Thermonuclear Experimental Reactor (ITER) has been delayed and will now begin in 2035. Delays to the ITER schedule may affect the availability of tritium for subsequent fusion devices, as the global CANDU-type fission reactor fleet begins to phase out over the coming decades. This study provides an up to date account of future tritium availability by incorporating recent uncertainties over the life extension of the global CANDU fleet, as well as considering the potential impact of tritium demand by other fusion efforts. Despite the delays, our projections suggest that CANDU tritium remains sufficient to support the full operation of ITER. However, whether there is tritium available for a DEMO reactor following ITER is largely uncertain, and is subject to numerous uncontrollable externalities. Further tritium demand may come from any number of private sector “compact fusion” start-ups which have emerged in recent years, all of which aim to accelerate the development of fusion energy. If the associated technical challenges can be overcome, compact fusion programmes have the opportunity to use tritium over the next two decades whilst it is readily available, and before full power DT operation on ITER starts in 2035. Assuming a similar level of performance is achievable, a compact fusion development programme, using smaller reactors operating at lower fusion power, would require smaller quantities of tritium than the ITER programme, leaving sufficient tritium available for multiple concepts to be developed concurrently. The development of concurrent fusion concepts increases the chances of success, as it spreads the risk of failure. Additionally, if full tritium breeding capability is not expected to be demonstrated in DEMO until after 2050, an opportunity exists for compact fusion programmes to incorporate tritium breeding technology in nearer-term devices. DD start-up, which avoids the need for external tritium for reactor start-up, is dependent upon full tritium breeding capability, and may be essential for large-scale commercial roll-out of fusion energy. As such, from the standpoint of availability and use of external tritium, a compact route to fusion energy may be more advantageous, as it avoids longer-term complications and uncertainties in the future supply of tritium.

WMGR: A Generic and Compact Routing Scheme for Data Center Networks

Data center networks (DCNs) connect hundreds and thousands of computers and, as a result of the exponential growth in their number of nodes, the design of scalable (compact) routing schemes plays a pivotal role in the optimal operation of the DCN. Traditional trends in the design of DCN architectures have led to solutions, where routing schemes and network topologies are interdependent, i.e., specialized routing schemes. Unlike these, we propose a routing scheme that is compact and generic, i.e., independent of the DCN topology, the word-metric-based greedy routing. In this scheme, each node is assigned to a coordinate (or label) in the word-metric space (WMS) of an algebraic group and then nodes forward packets to the closest neighbor to the destination in this WMS. We evaluate our scheme and compare it with other routing schemes in several topologies. We prove that the memory space requirements in nodes and the forwarding decision time grow sub-linearly (with respect to n, the number of nodes) in all of these topologies. The scheme finds the shortest paths in topologies based on Cayley graphs and trees (e.g. Fat tree), while in the rest of topologies, the length of any path is stretched by a factor that grows logarithmically (with respect to n). Moreover, the simulation results show that many of the paths remain far below this upper bound.

Design of 0–3 type nanocomposites using hydrothermal sintering

We report here the successful design of 0–3 type nanocomposites where 30 nm ferromagnetic metallically conducting cores of manganite La0.66Sr0.34MnO3 (LSMO) are discretely distributed in an insulating silica matrix. Starting from LSMO@SiO2 core@shell nanoparticles, hydrothermal sintering process was used as a low temperature densification route (300 °C, 350 MPa, 90 min) in presence of 0.2 M aqueous sodium hydroxide solution. This process based on a pressure solution creep in the contact zones between nanoparticles allows the design of complex microstructures preventing the grain growth of the cores and the formation of interphases between the cores and the matrix.

Dist-Coop: Distributed Cooperative Transmission in UWSNs using Optimization Congestion Control and Opportunistic Routing

One of the real issues in UWSN is congestion control. The need is to plan an optimized congestion control scheme which enhances the network life time and in addition limits the usage of energy in data transmission from source to destination. In this paper, we propose a routing protocol called Dist-Coop in UWSN. Dist-Coop is a distributed cooperation based routing scheme which uses mechanism for optimized congestion control in noisy links of underwater environment. It is compact, energy proficient and high throughput opportunistic routing scheme for UWSN. In this proposed protocol architecture, we present congestion control with cooperative transmission of data packets utilizing relay sensors. The final objective is to enhance the network life time and forward information utilizing cooperation procedure, limiting energy consumption amid transmission of information. At destination node, combining strategy utilized is based on Signal-to-Noise Ratio (SNRC). Simulation results of Dist-Coop scheme indicate better outcomes in terms of energy consumption, throughput and network lifetime in contrast with Co-UWSN and EH-UWSN routing protocols. Dist-Coop has expended substantially less energy and better throughput when contrasted with these protocols.

Characteristics of FeCuAl Powder Compacts Formed through Uniaxial Die Compaction Route

This paper presents the development of FeCuAl powder compacts through uniaxial die compaction process. Iron powder ASC 100.29 was mechanically mixed with other elemental powders, i.e., copper (Cu), and aluminum (Al) for 30 minutes at a rotation of 30 rpm. The feedstock was subsequently shaped at three different temperatures, i.e., 30°C, 150°C, and 200°C through simultaneous upward and downward axial loading of 325 MPa. The as-pressed samples termed as green compacts were then sintered in argon gas fired furnace at 800°C for three different holding times, i.e., 30, 60, and 90 min at a rate of 10°C/min. The sintered samples were characterized for their relative density, electrical resistivity, and bending strength. The microstructure of the sintered samples was also evaluated through scanning electron microscopy (SEM). The results revealed that the sample formed at 150°C and sintered for 30 min obtained the best final characteristics, i.e., higher relative density, lower volumetric expansion and electrical resistivity, and higher bending strength. Microstructure evaluation also revealed that the sample formed at 150°C and sintered for 30 min obtained more homogeneous distribution of grains and less interconnected pores compared to the other samples.

Enhanced toughness of zirconia ceramics with graphene platelets consolidated by spark plasma sintering

AbstractGraphene platelets reinforced zirconia (GPLs/ZrO2) composites were prepared by spark plasma sintering in the present work. The effects of GPLs content on the densification route, microstructure feather, mechanical properties, and aging behaviors of such composites were investigated. In spite of the impeding effect of GPLs, high relative density of 98% was achieved for the composites owing to the uniform dispersion of GPLs. The addition of GPLs contributed to enhanced fracture toughness of the composites; when the added content was 1.0 wt.%, its fracture toughness reached up to 8.6 MPa·m1/2. Also, aging behavior of the GPLs/ZrO2 composites was investigated at 134°C for 24 hours. The monolithic ZrO2 ceramic and GPLs/ZrO2 composites presented residual ratio of 55% and 72% in fracture toughness, respectively. Thus, the incorporation of GPLs inhibited phase transformation from tetragonal phase to monoclinic phase of zirconia.

Porous titanium alloy/hydroxyapatite composite using powder compaction route

Porous titanium alloy/hydroxyapatite composite using powder compaction route

Routing at Large Scale: Advances and Challenges for Complex Networks

A wide range of social, technological and communication systems can be described as complex networks. Scale-free networks are one of the well known classes of complex networks in which nodes� degrees follow a power-law distribution. The design of scalable, adaptive and resilient routing schemes in such networks is very challenging. In this article we present an overview of required routing functionality, categorize the potential design dimensions of routing protocols among existing routing schemes, and analyze experimental results and analytical studies performed so far to identify the main trends/trade-offs and draw main conclusions. Besides traditional schemes such as hierarchical/shortest-path path-vector routing, the article pays attention to advances in compact routing and geometric routing since they are known to significantly improve scalability in terms of memory space. The identified trade-offs and the outcomes of this overview enable more careful conclusions regarding the (un-)suitability of different routing schemes to large-scale complex networks and provide a guideline for future routing research.

Synthesis and Characterization of Bone & Teeth Ash and Analysis of Their Influence on the Properties of Bone China

The work was done to understand the effects of naturally occurred bone and teeth ash on the physical as well as mechanical properties of bone china products. Both bone and teeth ash was prepared following conventional thermal decomposition method. Locally found cattle bones and tooth was utilized for this purpose. Three different routes of powder or ash preparation i.e. boiling-wood firing, excavating-calcination and boiling-calcination were followed. The calcination temperature was fixed at 950°C-2 hours. After that, density and phase identification of ash was carried out. Finally, bone china product was manufactured using powder compaction and slip casting route. Firing was done at a constant temperature (1150°C-2 hours). Further characterizations (density, percent firing shrinkage, percent water absorption and modulus of rupture measurement) of the sintered samples were evaluated. Boiling-calcination route was found to be the most superlative route. However, enhanced properties of bone china were obtained by the addition of teeth ash.

Compact routing messages in self-healing trees

Existing compact routing schemes, e.g., Thorup and Zwick [4] and Chechik [6] often have no means to tolerate failures, once the system has been set up and started. This paper presents, to our knowledge, the first self-healing compact routing scheme. Besides, our schemes are developed for low memory nodes and are compact schemes, meaning they require only O(log2⁡n) bits memory.We introduce two algorithms of independent interest: The first is CompactFT, a novel compact version of the self-healing algorithm Forgiving Tree of Hayes et al. [7] that uses only O(log⁡n) bits local memory. The second algorithm (CompactFTZ) combines CompactFT with Thorup–Zwick's tree-based compact routing scheme [4] to produce a compact self-healing routing scheme. In the self-healing model, the adversary deletes nodes one at a time and the affected nodes self-heal locally by adding few edges. We introduce the bounded-memory self-healing model, where the memory each node need to use for the self-healing algorithm is bounded. CompactFT recovers from each attack in only O(1) time and Δ messages, with only +3 degree increase and O(log⁡Δ) graph diameter increase, over any sequence of deletions (Δ is the initial maximum degree).Additionally, CompactFTZ guarantees delivery of a packet sent from sender s as long as the receiver t has not been deleted, with only an additional O(ylog⁡Δ) latency, where y is the number of nodes that have been deleted on the path between s and t. If t has been deleted, s gets informed and the packet is removed from the network. CompactFTZ uses only O(log⁡n) bits memory for local fields (such as routing tables) and O(log2⁡n) bits for the routing labels, thus requiring O(log2⁡n) bits overall.

Mechanical and Corrosion Behavior of New Generation Ti-45Nb Porous Alloys Implant Devices

Strategies to improve the mechanical compatibility of Ti-based materials for hard tissue implant applications are directed towards significant stiffness reduction by means of the adjustment of suitable β-phases and porous device architectures. In the present study, the effect of different compaction routes of the gas-atomized β-Ti-45Nb powder on the sample architecture, porosity, and on resulting mechanical properties in compression was investigated. Green powder compacted and sintered at 1000 °C had a porosity varying between 8% and 12%, strength between 260 and 310 MPa, and Young’s modulus ranging between 18 and 21 GPa. Hot pressing of the powder without or with subsequent sintering resulted in microporosity varying between 1% and 3%, ultimate strength varying between 635 and 735 MPa, and Young’s modulus between 55 and 69 GPa. Samples produced with NaCl space-holder by hot-pressing resulted in a macroporosity of 45% and a high strength of ˃200 MPa, which is higher than the strength of a human cortical bone. Finally, the corrosion tests were carried out to prove that the presence of residual NaCl traces will not influence the performance of the porous implant in the human body.

On Hierarchical Routing in Doubling Metrics

We study the problem of routing in doubling metrics and show how to perform hierarchical routing in such metrics with small stretch and compact routing tables (i.e., with a small amount of routing information stored at each vertex). We say that a metric ( X , d ) has doubling dimension dim(<i<X</i<) at most α if every ball can be covered by 2 α balls of half its radius. (A doubling metric is one whose doubling dimension dim(<i<X</i<) is a constant.) We consider the metric space induced by the shortest-path distance in an underlying undirected graph G . We show how to perform (1 + τ)-stretch routing on such a metric for any 0 < τ ≤ 1 with routing tables of size at most (α/τ) O (α) log Δlog δ bits with only (α/τ) O (α) log Δ entries , where Δ is the diameter of the graph, and δ is the maximum degree of the graph G ; hence, the number of routing table entries is just τ − O (1) log Δ for doubling metrics. These results extend and improve on those of Talwar (2004). We also give better constructions of sparse spanners for doubling metrics than those obtained from the routing tables earlier; for τ > 0, we give algorithms to construct (1 + τ)-stretch spanners for a metric ( X , d ) with maximum degree at most (2 + 1/τ) O(dim(X)) , matching the results of Das et al. for Euclidean metrics.

Hybrid fault tolerant routing algorithm in NoC

Network-on-Chip has been a growing design paradigm with the rise in Multi-Processor System on Chip (MPSoCs) primarily due to its scalability. While regular meshes (2 or 3-dimensional) are the usual proposal for such a paradigm, a real chip may not follow it. Heterogeneous cores, hardware failures or manufacturing defects can possibly cause irregular topologies in a Network-on-Chip. Selection of a routing algorithm is an important challenge in NoC design as it affects power consumption, communication latency and overall system performance. Routing can be supported in such faulty environment by use of routing tables. But this is not a scalable solution as table size grows with network size. Logic Based Distributed Routing (LBDR) is proposed as a new routing implementation technique which offers compact routing implementation and fault tolerance without use of routing table. In this paper we propose a Hybrid Fault Tolerant Routing Algorithm (HFTRA), which aims to provide fault tolerance support in presence of on-chip link failures. Proposed routing is implemented with LBDR scheme. Analysis of the method has shown the effectiveness of proposed scheme as compared to routing tables when implemented using LBDR.

A Multipath Prefix Routing for Wireless Sensor Networks

When a spanning tree is built on top of a wireless network and an appropriate labelling scheme is applied, the complexity of the routing mechanism in terms of memory usage and control messages can be drastically reduced using compact routing. In this paper, we propose multipath prefix routing (MPR), a multipath routing protocol for wireless sensor networks. MPR is a hybrid (both reactive and proactive) protocol that operates on an already built spanning tree rooted at the sink (the collect station). Besides the tree path, additional paths are built based on an appropriate labelling scheme and neighbourhood relationships. For practical implementation, we propose and evaluate two different labelling schemes. We mainly show that in a perfect W-ary tree, the additional number of bits required to encode labels is at most $$(H-1)$$(H-1) where H is the height of the tree. Finally, we apply MPR to the ZigBee standard and evaluate its performance using simulations. MPR has a small state routing while control messages overhead is maintained low compared to traditional multipath routing protocols.

Effects of sintering schedule on the characteristics of Fe-based powder compacts formed through warm compaction route

This paper presents the sintering characteristics of Fe-based powder compacts formed through the warm compaction method. Iron powder ASC100.29 (73 wt%), chromium powder (22 wt%), and aluminium powder (5 wt%) were mixed mechanically for 60 mins in preparing the feedstock. The powder mixture was subsequently compacted at 200ºC through simultaneous loading of 325 MPa from upper and lower punches. The defectfree green compacts were then sintered in an argon gas fired furnace at a rate of 10ºC/min by varying the sintering time (30, 60, and 90 mins) and temperature (600, 750, and 900ºC), respectively. The sintered samples were characterized through physical and mechanical properties and their microstructures were analysed through scanning electron microscopy. The results revealed that sintering at 900ºC for 90 mins contributed to the highest volumetric expansion and relative density change, which are not expected in the powder metallurgy industries. A moderate sintering temperature of 750ºC for a holding time of 60 mins was found to produce a sintered sample with higher bending strength. In these sintering conditions, better dispersion of the alloyed elements is also observed.

Scale-Free Compact Routing Schemes in Networks of Low Doubling Dimension

We consider compact routing schemes in networks of low doubling dimension, where the doubling dimension is the least value α such that any ball in the network can be covered by at most 2 α balls of half radius. There are two variants of routing-scheme design: (i) labeled (name-dependent) routing, in which the designer is allowed to rename the nodes so that the names (labels) can contain additional routing information, for example, topological information; and (ii) name-independent routing, which works on top of the arbitrary original node names in the network, that is, the node names are independent of the routing scheme. In this article, given any constant ϵ ∈ (0, 1) and an n -node edge-weighted network of doubling dimension α ∈ O (loglog n ), we present —a (1 + ϵ)-stretch labeled compact routing scheme with ⌈log n ⌉-bit routing labels, O (log 2 n /loglog n )-bit packet headers, and ((1/ϵ) O (α) log 3 n )-bit routing information at each node; —a (9 + ϵ)-stretch name-independent compact routing scheme with O (log 2 n /loglog n )-bit packet headers, and ((1/ϵ) O (α) log 3 n )-bit routing information at each node. In addition, we prove a lower bound: any name-independent routing scheme with o ( n (ϵ/60) 2 ) bits of storage at each node has stretch no less than 9 − ϵ for any ϵ ∈ (0, 8). Therefore, our name-independent routing scheme achieves asymptotically optimal stretch with polylogarithmic storage at each node and packet headers. Note that both schemes are scale-free in the sense that their space requirements do not depend on the normalized diameter Δ of the network. We also present a simpler nonscale-free (9 + ϵ)-stretch name-independent compact routing scheme with improved space requirements if Δ is polynomial in n .

Trap Array: A Unified Model for Scalability Evaluation of Geometric Routing

Scalable routing for large-scale wireless networks needs to find near shortest paths with low state on each node, preferably sublinear with the network size. Two approaches are considered promising toward this goal: compact routing and geometric routing (geo-routing). To date, the two lines of research have been largely independent, perhaps because of the distinct principles they follow. In particular, it remains unclear how they compare to each other in the worst case, despite extensive experimental results showing the superiority of one or another in particular cases. We develop a novel Trap Array topology model that provides a unified framework to uncover the limiting behavior of 10 representative geo-routing algorithms. We present a series of new theoretical results, in comparison to the performance of compact routing as a baseline. In light of their pros and cons, we further design a Compact Geometric Routing (CGR) algorithm that attempts to leverage the benefits of both approaches. Theoretical analysis and simulations show the advantages of the topology model and the algorithm.

Effects of Compaction and Sintering Temperature to the Alloyability of FeCrCu Powder Mixture

This paper presents the alloyability of FeCrCu powder compacts formed through warm powder compaction route. A lab-scale uni-axial die compaction rig was designed and fabricated which enabled the powder forming at elevated temperature. Iron powder ASC 100.29 was mechanically mixed with other alloying elements, i.e., copper (Cu) and chromium (Cr) as well as carbon (C) as additive for 60 minutes. Green samples were formed at 30°C (room temperature), 100°C, and 180°C through simultaneous upward and downward axial loadings. The defect-free green compacts were subsequently sintered in argon gas fired furnace at 900°C and 1000°C for 60 minutes at a rate of 5°C/minute. The alloyability of the sintered products was analyzed through XRD testing. The compressive strength of the sintered samples was also measured. The results revealed that FeCrCu alloy was formed at different intensity depended upon the forming and sintering temperature. The compressive strength was found to be highest for sample formed at 180°C and sintered at 1000°C.

A Compact Routing based Mapping System for the Locator/ID Separation Protocol (LISP)

The Internet and its associated global routing tables are growing at an alarming rate. Will the current routing infrastructure be able to scale itself to sustain such growth? Over the past several years, many efforts have been made to resolve this important issue. This paper offers a novel solution to this serious problem by proposing and presenting an experimental mapping system called Compact Routing based Mapping (CRM). The idea here is to combine the perceived benefits of both Compact Routing and Locator/Identifier Separation Protocol (LISP). In CRM, the critical functions that affect the scalability of the routing system are grounded to the theory of Compact Routing; so that we might overcome the shortcomings of LISP-ALT. We mitigated Compact Routing’s presumption of a static network by reusing LISP’s registration messages and choosing landmarks dynamically based on their capability to aggregate. The key objective of this paper is to provide proof of concept, to give first-hand experience regarding the complicacies that arise with the actual development of such a mapping system. Our work also includes a comprehensive comparison between CRM and LISP-ALT. The results suggest that, CRM would be feasible in the current Internet if deployed and it would be far less expensive than LISP-ALT.