A review and comparison of efficient flooding schemes for on-demand routing protocols on mobile ad hoc networks (MANETs)

Since the basic components of ad hoc wireless networks are mostly battery-operated portable devices, power conservation is one of the central issues of such networks. Power-conservative designs for ad hoc networks pose many challenges due to the lack of central coordination facilities. Existing on-demand routing protocols perform route discovery by flooding the network with a query message requesting a route to the destination. Flooding is used because of its simplicity and greater success in finding the best route between the source and destination available at that time of route discovery. However, as flooding involves querying all reachable network nodes, frequent flooding can rapidly deplete the energy reserved at each node. In addition to consuming significant portions of the available network bandwidth. Further, as the number of communicating nodes increases, more congestion, contention, and collisions can be expected. This paper reviews and compares approaches for optimizing bandwidth efficiency of route discovery, where several efficient flooding schemes have been presented based on different techniques to solve the problems related with the traditional blind flooding

Grounded Theory of Consumer Loyalty: A Perspective through Video Game Addiction

Game addiction has become an extremely important topic in psychology researchers, particularly in understanding and explaining why individuals become addicted (to video games). In previous studies, effect of online game addiction on social responsibilities, health problems, government action, and the behaviors of individuals to purchase and the causes of making individuals addicted on the video games has been discussed. Extending these concepts in marketing, it could be argued than the phenomenon could enlighten and extending our understanding on consumer loyalty. This study took the Grounded Theory approach, and found that motivation, satisfaction, fulfillments, exploration and achievements to be part of the important elements that builds consumer loyalty

Replay Attacks and Defenses Against Cross-shard Consensus in Sharded Distributed Ledgers

We present a family of replay attacks against sharded distributed ledgers targeting cross-shard consensus protocols, such as the recently proposed Chainspace and Omniledger. They allow an attacker, with network access only, to double-spend or lock resources with minimal efforts. The attacker can act independently without colluding with any nodes, and succeed even if all nodes are honest; most of the attacks can also exhibit themselves as faults under periods of asynchrony. These attacks are effective against both shard-led and client-led cross-shard consensus approaches. We present Byzcuit-a new cross-shard consensus protocol that is immune to those attacks. We implement a prototype of Byzcuit and evaluate it on a real cloud-based testbed, showing that our defenses impact performance minimally, and overall performance surpasses previous works

Charging infrastructure for commercial electric vehicles: Challenges and future works

The journey towards transportation electrification started with small electric vehicles (i.e., electric cars), which have enjoyed an increasing level of global interest in recent years. Electrification of commercial vehicles (e.g., trucks) seems to be a natural progression of this journey, and many commercial vehicle manufacturers have shifted their focus on medium- and heavy-duty vehicle electrification over the last few years. In this paper, we present a comprehensive review and analysis of the existing works presented in the literature on commercial vehicle charging. The paper starts with a brief discussion on the significance of commercial vehicle electrification, especially heavy- and medium-duty vehicles. The paper then reviews two major charging strategies for commercial vehicles, namely the return-to-base model and the on route charging model. Research challenges related to the return-to-base model are then analysed in detail. Next, different methods to charge commercial vehicles on route during their driving cycles are summarized. The paper then analyzes the challenging issues related to charging commercial vehicles at public charging stations. Future works relevant to these challenges are highlighted. Finally, the possibility of accommodating vehicle to grid technology for commercial vehicles is discussed

Isolation and characterization of microsatellite loci from two inbreeding bark beetle species (Coccotrypes)

We developed 14 microsatellite markers in Coccotrypes carpophagus and 14 in C. dactyliperda. These loci will be used for studying genetic structure and the level of inbreeding in populations in the Canary Islands and Madeira. As a result of long-term inbreeding, genetic variability is relatively low in these bark beetle species. We found one to five alleles per locus in 29 C. carpophagus and 41 C. dactyliperda from various localities. Eleven of the markers developed for C. carpophagus amplified in C. dactyliperda and seven of the markers developed for C. dactyliperda amplified in C. carpophagus

SoK: Consensus in the Age of Blockchains

The core technical component of blockchains is consensus: how to reach agreement among a distributed network of nodes. A plethora of blockchain consensus protocols have been proposed---ranging from new designs, to novel modifications and extensions of consensus protocols from the classical distributed systems literature. The inherent complexity of consensus protocols and their rapid and dramatic evolution makes it hard to contextualize the design landscape. We address this challenge by conducting a systematization of knowledge of blockchain consensus protocols. After first discussing key themes in classical consensus protocols, we describe: (i) protocols based on proof-of-work; (ii) proof-of-X protocols that replace proof-of-work with more energy-efficient alternatives; and (iii) hybrid protocols that are compositions or variations of classical consensus protocols. This survey is guided by a systematization framework we develop, to highlight the various building blocks of blockchain consensus design, along with a discussion on their security and performance properties. We identify research gaps and insights for the community to consider in future research endeavours

Computation of Sound Generated by Viscous Flow Over a Circular Cylinder

The Lighthill acoustic analogy approach combined with Reynolds-averaged Navier Stokes is used to predict the sound generated by unsteady viscous flow past a circular cylinder assuming a correlation length of 10 cylinder diameters. The two-dimensional unsteady flow field is computed using two Navier-Stokes codes at a low Mach number over a range of Reynolds numbers from 100 to 5 million. Both laminar flow as well as turbulent flow with a variety of eddy viscosity turbulence models are employed. Mean drag and Strouhal number are examined, and trends similar to experiments are observed. Computing the noise within the Reynolds number regime where transition to turbulence occurs near the separation point is problematic: laminar flow exhibits chaotic behavior and turbulent flow exhibits strong dependence on the turbulence model employed. Comparisons of far-field noise with experiment at a Reynolds number of 90,000, therefore, vary significantly, depending on the turbulence model. At a high Reynolds number outside this regime, three different turbulence models yield self-consistent results

Biofilm reactors for industrial bioconversion processes: employing potential of enhanced reaction rates

This article describes the use of biofilm reactors for the production of various chemicals by fermentation and wastewater treatment. Biofilm formation is a natural process where microbial cells attach to the support (adsorbent) or form flocs/aggregates (also called granules) without use of chemicals and form thick layers of cells known as "biofilms." As a result of biofilm formation, cell densities in the reactor increase and cell concentrations as high as 74 gL(-1 )can be achieved. The reactor configurations can be as simple as a batch reactor, continuous stirred tank reactor (CSTR), packed bed reactor (PBR), fluidized bed reactor (FBR), airlift reactor (ALR), upflow anaerobic sludge blanket (UASB) reactor, or any other suitable configuration. In UASB granular biofilm particles are used. This article demonstrates that reactor productivities in these reactors have been superior to any other reactor types. This article describes production of ethanol, butanol, lactic acid, acetic acid/vinegar, succinic acid, and fumaric acid in addition to wastewater treatment in the biofilm reactors. As the title suggests, biofilm reactors have high potential to be employed in biotechnology/bioconversion industry for viable economic reasons. In this article, various reactor types have been compared for the above bioconversion processes

A charging strategy for large commercial electric vehicle fleets

The popularity of Commercial Electric Vehicles (CEVs) has experienced a surge in recent years, particularly in urban vocational contexts, as a means of advancing towards the goal of attaining net-zero emissions by 2050. The return-to-base charging strategy, which involves charging CEVs at depots, has become a prevalent practice for smaller CEV fleets. Nevertheless, for larger CEV fleets, the limited charging capacity at depots presents a significant challenge, leading to a reliance on both limited depot charging infrastructure and public charging infrastructure. This reliance can have a substantial impact on both the operational costs and the sustainability of logistics services. To address these challenges, this study proposes a new charging strategy for managing the charging of large CEV fleets. The proposed strategy coordinates the charging of CEVs at depots and public charging stations. The strategy is formulated as a constraint optimization problem and takes into consideration operational schedules, demand charges, and the characteristics of public charging stations. The results of this study demonstrate the effectiveness of the proposed strategy in optimizing CEV charging at different stations, preserving the continuity of logistics services, and reducing total travel costs by 30% compared to existing solutions. This study offers a solution to the challenges faced by large CEV fleets in their efforts to achieve cost-effective and sustainable charging solutions

Delayed dislocation following metal-on-polyethylene hip replacement due to “silent” trunnion corrosion

AimsWe present a case series of ten metal-on-polyethylene total hip arthroplasties (MoP THAs) with delayed dislocation associated with unrecognised adverse local tissue reaction due to corrosion at the trunnion and pseudotumour formation.MethodsThe diagnosis was not suspected in nine of the ten patients (six female/four male; mean age 66 years), despite treatment in a specialist unit (mean time from index surgery to revision was 58 months, 36 to 84). It was identified at revision surgery and subsequently confirmed by histological examination of resected tissue. Pre-operative assessment and culture results ruled out infection. A variety of treatment strategies were used, including resection of the pseudotumour and efforts to avoid recurrent dislocation.ResultsThe rate of complications was high and included three deep infections, two patients with recurrent dislocation, and one recurrent pseudotumour.ConclusionThis series (mean follow-up of 76 months following index procedure and 19 months following revision THA) demonstrates that pseudotumour is an infrequent but important contributor to delayed instability following MoP THA. It is easy to overlook in the differential diagnosis, especially if the alignment of the components is less than optimal, leading to an assumption that malalignment is the cause of the dislocation. The instability is likely to be multifactorial and the revision surgery is complex. Take home message: Due to the high complication rate associated with revision in this cohort, the diagnosis should be borne in mind when counselling patients regarding the risks of revision surgery. Cite this article: Bone Joint J 2016;98-B:187–93.</jats:sec