Growth and thermal stability of TiN/ZrAlN: Effect of internal interfaces

Wear resistant hard films comprised of cubic transition metal nitride (c-TMN) and metastable c-AlN with coherent interfaces have a confined operating envelope governed by the limited thermal stability of metastable phases. However, equilibrium phases (c-TMN and wurtzite(w)-AlN) forming semicoherent interfaces during film growth offer higher thermal stability. We demonstrate this concept for a model multilayer system with TiN and ZrAlN layers where the latter is a nanocomposite of ZrN- and AlN- rich domains. The interfaces between the domains are tuned by changing the AlN crystal structure by varying the multilayer architecture and growth temperature. The interface energy minimization at higher growth temperature leads to formation of semicoherent interfaces between w-AlN and c-TMN during growth of 15 nm thin layers. Ab initio calculations predict higher thermodynamic stability of semicoherent interfaces between c-TMN and w-AlN than isostructural coherent interfaces between c-TMN and c-AlN. The combination of a stable interface structure and confinement of w-AlN to nm-sized domains by its low solubility in c-TMN in a multilayer, results in films with a stable hardness of 34 GPa even after annealing at 1150 °C.Peer ReviewedPostprint (author's final draft

Self-organized nanostructuring in Zr0.69Al0.31N thin films studied by atom probe tomography

We have applied atom probe tomography (APT) to analyze self-organizing structures of wear-resistant Zr0.69Al0.31N thin films grown by magnetron sputtering. Transmission electron microscopy shows that these films grow as a three-dimensional nanocomposite, consisting of interleaved lamellae in a labyrinthine structure, with an in-plane size scale of ~ 5 nm. The structure was recovered in the Al APT signal, while the Zr and N data lacked structural information. The onset of the self-organized labyrinthine growth was observed to occur by surface nucleation, 5–8 nm above the MgO substrate, due to increasing Zr–Al compositional fluctuations during elemental segregation. At a final stage, the labyrinthine growth mode was observed to be interrupted by the formation of larger ZrN grains

Experimental evaluation of a software defined radio-based prototype for a disaster response cellular network

In post disaster situations it is vital to restore voice and data communication services quickly. Currently, portable wireless systems are used as a temporary solution. However, these solutions have a lengthy setup, limited coverage, and typically require the use of expensive satellite backhaul. Solutions based on cognitive radio mesh networks have been proposed, to exploit self-configuration and spectrum agility. To evaluate their potential, we build a software-radio-based prototype for a multi-cell network that uses an IEEE 802.11's unlicensed wireless communication band for backhaul, and an open-source GSM stack for access. The prototype provides voice communication services. We evaluate the prototype in an open environment. We demonstrate that under the right conditions, the system can support large numbers of simultaneous calls with acceptable quality. However, when the unlicensed band is heavily used, call quality quickly degrades because of interference on the backhaul link. We conclude that in order to provide acceptable quality of service it is desirable to exploit idle licensed spectrum for backhaul communication between base stations

Cognitive radio policy-based adaptive blind rendezvous protocols for disaster response

In disaster scenarios, with damaged network infrastructure, cognitive radio (CR) can be used to provide temporary network access in the first few hours. Since spectrum occupancy will be unknown, the radios must rely on spectrum sensing and opportunistic access. An initial goal is to establish rendezvous between CR nodes to set up the network. The unknown primary radio (PR) activity and CR node topology makes this a challenging task. Existing blind rendezvous strategies provide guarantees on time to rendezvous, but assume channels with no PR activity and no external interferers. To handle this problem of blind multi-node rendezvous in the presence of primary users, we propose an Extended Modular Clock Algorithm which abandons the guarantee on time to rendezvous, an information exchange mechanism for the multi-node problem, and various cognitive radio operating policies. We show that the adapted protocols can achieve up to 80% improvement in the expected time to rendezvous and reduce the harmful interference caused to the primary radio

A cognitive radio-based fully blind multihop rendezvous protocol for unknown environments

In Cognitive Radio networking, the blind rendezvous problem is when two or more nodes must establish a link, but where they have no predefined schedule or common control channel for doing so. The problem becomes more challenging when the information about the existence of other nodes in the network, their topology, and primary user activity are also unknown, identified here as a fully blind rendezvous problem. In this paper, a novel and fully blind multihop (FBM) rendezvous framework is proposed with an extended modular clock algorithm (EMCA). The EMCA-FBM is a fully blind multihop rendezvous protocol as it assumes the number of nodes, primary radio activity and topology information as unknown. It is shown to work with different Cognitive Radio operating policies to achieve adaptiveness towards the unknown primary radio activity, and self-organization for autonomously handling the rendezvous process by using transmission schedules. It is capable of working without any information of neighbor nodes and terminating the rendezvous process whenever all or sufficient nodes are discovered. The proposed FBM is also shown to work as a general framework to extend existing single hop rendezvous protocols to work as a multihop rendezvous protocol. In comparison with other modified blind rendezvous strategies for multihop network, the combination of the proposed EMCA-FBM protocol and operating policies is shown to be effective in improving the average time to rendezvous (up to 70%) and neighbor discovery accuracy (almost 100%) while reducing harmful interference

An Efficient Eulerian Video Magnification Technique for Micro-biology Applications

The micro-biology videos often contain motions of particles which are not visible to naked eye. Therefore an efficient motion magnification technique is required to magnify these motions. A time efficient eulerian video magnification technique for micro-biological applications is proposed. The proposed technique utilizes the concept of time and spatial uniformity to reduce the computational complexity. Simulation results reveal that the proposed scheme is almost four times efficient and more accurate as compared to state of art video magnification technique

Neutron optical tuning of Fe/11B4CTi multilayers for optimal polarization and increased reflectivity for polarizing neutron optics

The concept of scattering length density tuning for improved polarization is investigated for Fe/11B4CTi multilayers and compared to the commonly used Fe/Si system in polarizing multilayer neutron optics. X-ray and neutron reflectivity, magnetization, and neutron polarization have been measured on such multilayers, highlighting differences from conventional Fe/Si multilayers. The multilayer systems were deposited with 25 {\AA} period thickness, a layer thickness ratio of 0.35 and 20 periods, using ion-assisted DC magnetron sputtering. Replacing Si with 11B4CTi for these multilayers showed an increase in reflectivity due to a reduction in interface width. By tuning the ratio between 11B4C and Ti in the non-magnetic layers, a broad range of scattering length density values was achieved, facilitating scattering length density contrast matching between layers for spin-down neutrons, thereby enhancing polarization. These findings demonstrate the potential of Fe/11B4CTi multilayers as a promising option for polarizing neutron optics and highlight the concept of scattering length density tuning in a large range using 11B4CTi

Cognitive radio for disaster response networks: survey, potential, and challenges

In the wake of a natural or man-made disaster, restoration of telecommunications is essential. First responders must coordinate their responses, immediate casualties require assistance, and all affected citizens may need to access information and contact friends and relatives. Existing access and core infrastructure may be damaged or destroyed, so to support the required services, new infrastructure must be rapidly deployed and integrated with undamaged resources still in place. This new equipment should be flexible enough to interoperate with legacy systems and heterogeneous technologies. The ability to selforganize is essential in order to minimize any delays associated with manual configuration. Finally, it must be robust and reliable enough to support mission-critical applications. Wireless systems can be more easily reconfigured than wired solutions to adapt to the various changes in the operating environment that can occur in a disaster scenario. A cognitive radio is one that can observe its operating environment, make decisions and reconfigure in response to these observations, and learn from experience. This article examines the use of cognitive radio technologies for disaster response networks and shows that they are ideally suited to fulfill the unique requirements of these networks. Key enabling technologies for realizing real-world cognitive radio networks for disaster response are discussed and core challenges are examined

Open versus closed surgical exposure of canine teeth that are displaced in the roof of the mouth

BACKGROUND: Palatally displaced canines or PDCs are upper permanent canines, commonly known as 'eye' teeth, that are displaced in the roof of the mouth. This can leave unsightly gaps, cause damage to the surrounding roots (which can be so severe that neighbouring teeth are lost or have to be removed) and, occasionally, result in the development of cysts. PDCs are a frequent dental anomaly, present in 2% to 3% of young people.Management of this problem is both time consuming and expensive. It involves surgical exposure (uncovering) followed by fixed braces for two to three years to bring the canine into alignment within the dental arch. Two techniques for exposing palatal canines are routinely used in the UK: the closed technique and the open technique. The closed technique involves uncovering the canine, attaching an eyelet and gold chain and then suturing the palatal mucosa back over the tooth. The tooth is then moved into position covered by the palatal mucosa. The open technique involves uncovering the canine tooth and removing the overlying palatal tissue to leave it uncovered. The orthodontist can then see the crown of the canine to align it. OBJECTIVES: To assess the effects of using either an open or closed surgical method to expose canines that have become displaced in the roof of the mouth, in terms of success and other clinical and patient-reported outcomes. SEARCH METHODS: Cochrane Oral Health's Information Specialist searched the following databases: Cochrane Oral Health's Trials Register (to 24 February 2017), the Cochrane Central Register of Controlled Trials (CENTRAL) (in the Cochrane Library, 2017, Issue 1), MEDLINE Ovid (1946 to 24 February 2017), and Embase Ovid (1980 to 24 February 2017). The US National Institutes of Health Ongoing Trials Register (ClinicalTrials.gov) and the World Health Organization International Clinical Trials Registry Platform were searched for ongoing trials. No restrictions were placed on the language or date of publication when searching the electronic databases. SELECTION CRITERIA: We included randomised and quasi-randomised controlled trials assessing young people receiving surgical treatment to correct upper PDCs. There was no restriction on age, presenting malocclusion or type of active orthodontic treatment undertaken. We included unilaterally and bilaterally displaced canines. DATA COLLECTION AND ANALYSIS: Two review authors independently screened the results of the electronic searches, extracted data and assessed the risk of bias in the included studies. We attempted to contact study authors for missing data or clarification where feasible. We followed statistical guidelines from the Cochrane Handbook for Systematic Reviews of Interventions for data synthesis. MAIN RESULTS: We included three studies, involving 146 participants. Two studies were assessed as being at high risk of bias.The main finding of the review was that the two techniques may be equally successful at exposing PDCs (risk ratio (RR) 0.99, 95% confidence interval (CI) 0.93 to 1.06; three studies, 141 participants analysed, low-quality evidence).One surgical failure was due to detachment of the gold chain (closed group). One study reported on complications following surgery and found two in the closed group: a post-operative infection requiring antibiotics and pain during alignment of the canine as the gold chain penetrated through the gum tissue of the palate.We were unable to pool data for dental aesthetics, patient-reported pain and discomfort, periodontal health and treatment time; however, individual studies did not find any differences between the surgical techniques (low- to very low-quality evidence). AUTHORS' CONCLUSIONS: Currently, the evidence suggests that neither the open or closed surgical technique for exposing palatally displaced maxillary canine teeth is superior for any of the outcomes included in this review; however, we considered the evidence to be low quality, with two of the three included studies being at high risk of bias. This suggests the need for more high-quality studies. Three ongoing clinical trials have been identified and it is hoped that these will produce data that can be pooled to increase the degree of certainty in these findings

GENETIC ANALYSIS FOR GRAIN YIELD AND VARIOUS MORPHOLOGICAL TRAITS IN MAIZE (ZEA MAYS L.) UNDER NORMAL AND WATER STRESS ENVIRONMENTS

ABSTRACT A genetic analysis study was carried out for various morphological traits in a complete 8 × 8 diallel cross of maize inbred lines under normal irrigation and drought conditions. Estimation of genetic components of variation and graphical presentation deduced that most of the traits like days to pollen shed, anthesis-silking interval, ear height, kernel rows per ear, 100-kernel weight, shelling percentage, grain yield per plant showed over-dominance type of inheritance under both normal and drought conditions unlike leaf rolling which showed partial dominance under normal but over-dominance type of inheritance under drought conditions. It can be inferred that because of over-dominance nature of inheritance of most of the yield related traits, heterosis breeding can be pursued to exploit high yielding hybrids with considerable drought tolerance