Dynamic response and robustness of tall buildings under blast loading

Recently, extensive research has been focused on the progressive collapse analysis of the multi-storey buildings. However, most of the research is based on the Alternative Path Method (APM) with sudden removal of the columns, ignoring the duration of the blast load working on the structures. In this paper, a 3-D numerical model with the direct simulation of blast load is proposed to study the real behaviour of a 20 storey tall building under the blast loading. A typical package bomb charge of 15 kg was detonated on the 12th floor. The corresponding dynamic response of structure was studied in details. The robustness of the building under blast load was assessed. Comparison between the proposed method and the APM was also made. It is found that, due to the uplift and downw ard pressure working on the slab, the column force under the direct blast simulation method is smaller than that of the alternative path method. The method to enhance the robustness of the buildings is also recommended

Theoretical assessment of progressive collapse capacity of reinforced concrete structures

The progressive collapse behaviour of reinforced concrete (RC) structures requires consideration of material and geometric non-linearity, concrete crushing and rebar fracture. Compressive arch action (CAA) and catenary action (CTA) are the main resisting mechanisms against progressive collapse following a column loss. Hence, many studies have concentrated on the development of CAA and CTA in RC beams, but without considering the effect of bar fracture and the reduction in beam effective depth due to concrete crushing. Taking these additional factors into account, an analytical model to predict the structural behaviour of RC beams under a column removal scenario was developed. The proposed model was evaluated and validated with the available experimental results. The evaluation and validation indicate that the proposed model can provide a reliable assessment of RC beam capacity against progressive collapse

Translation of evidence-based Assistive Technologies into stroke rehabilitation: Users' perceptions of the barriers and opportunities

Background: Assistive Technologies (ATs), defined as "electrical or mechanical devices designed to help people recover movement", demonstrate clinical benefits in upper limb stroke rehabilitation; however translation into clinical practice is poor. Uptake is dependent on a complex relationship between all stakeholders. Our aim was to understand patients', carers' (P&Cs) and healthcare professionals' (HCPs) experience and views of upper limb rehabilitation and ATs, to identify barriers and opportunities critical to the effective translation of ATs into clinical practice. This work was conducted in the UK, which has a state funded healthcare system, but the findings have relevance to all healthcare systems. Methods. Two structurally comparable questionnaires, one for P&Cs and one for HCPs, were designed, piloted and completed anonymously. Wide distribution of the questionnaires provided data from HCPs with experience of stroke rehabilitation and P&Cs who had experience of stroke. Questionnaires were designed based on themes identified from four focus groups held with HCPs and P&Cs and piloted with a sample of HCPs (N = 24) and P&Cs (N = 8). Eight of whom (four HCPs and four P&Cs) had been involved in the development. Results: 292 HCPs and 123 P&Cs questionnaires were analysed. 120 (41%) of HCP and 79 (64%) of P&C respondents had never used ATs. Most views were common to both groups, citing lack of information and access to ATs as the main reasons for not using them. Both HCPs (N = 53 [34%]) and P&C (N = 21 [47%]) cited Functional Electrical Stimulation (FES) as the most frequently used AT. Research evidence was rated by HCPs as the most important factor in the design of an ideal technology, yet ATs they used or prescribed were not supported by research evidence. P&Cs rated ease of set-up and comfort more highly. Conclusion: Key barriers to translation of ATs into clinical practice are lack of knowledge, education, awareness and access. Perceptions about arm rehabilitation post-stroke are similar between HCPs and P&Cs. Based on our findings, improvements in AT design, pragmatic clinical evaluation, better knowledge and awareness and improvement in provision of services will contribute to better and cost-effective upper limb stroke rehabilitation. © 2014 Hughes et al.; licensee BioMed Central Ltd

The role of space in the security and defence policy of Turkey. A change in outlook: Security in space versus security from space

Space and security domains are strongly related with each other. Nowadays, space is an indispensable part of security and defence policy, and it is increasingly becoming a critical infrastructure for strategic Command, Control, Communications, Computers, Intelligence, Surveillance and Reconnaissance (C4ISR) systems. However, space is vulnerable itself to the new space threats. This study reviews the current and near future space role in Turkey's security and defence policy and aims to address the threats against space based capabilities. To provide security from space, space based systems shall themselves need to be secure in space to warrant the security. The concept of security from space starts with space security, in other words the security in space. This paper also highlights the emerging technological opportunities for these space threats to be secure in space in order to provide the security from space. According to the relevant taxonomy, a categorized opportunity proposal for more robust and resilient space/satellite projects' architecture is proposed for Turkey

Global navigation satellite systems performance analysis and augmentation strategies in aviation

In an era of significant air traffic expansion characterized by a rising congestion of the radiofrequency spectrum and a widespread introduction of Unmanned Aircraft Systems (UAS), Global Navigation Satellite Systems (GNSS) are being exposed to a variety of threats including signal interferences, adverse propagation effects and challenging platform-satellite relative dynamics. Thus, there is a need to characterize GNSS signal degradations and assess the effects of interfering sources on the performance of avionics GNSS receivers and augmentation systems used for an increasing number of mission-essential and safety-critical aviation tasks (e.g., experimental flight testing, flight inspection/certification of ground-based radio navigation aids, wide area navigation and precision approach). GNSS signal deteriorations typically occur due to antenna obscuration caused by natural and man-made obstructions present in the environment (e.g., elevated terrain and tall buildings when flying at low altitude) or by the aircraft itself during manoeuvring (e.g., aircraft wings and empennage masking the on-board GNSS antenna), ionospheric scintillation, Doppler shift, multipath, jamming and spurious satellite transmissions. Anyone of these phenomena can result in partial to total loss of tracking and possible tracking errors, depending on the severity of the effect and the receiver characteristics. After designing GNSS performance threats, the various augmentation strategies adopted in the Communication, Navigation, Surveillance/Air Traffic Management and Avionics (CNS + A) context are addressed in detail. GNSS augmentation can take many forms but all strategies share the same fundamental principle of providing supplementary information whose objective is improving the performance and/or trustworthiness of the system. Hence it is of paramount importance to consider the synergies offered by different augmentation strategies including Space Based Augmentation System (SBAS), Ground Based Augmentation System (GBAS), Aircraft Based Augmentation System (ABAS) and Receiver Autonomous Integrity Monitoring (RAIM). Furthermore, by employing multi-GNSS constellations and multi-sensor data fusion techniques, improvements in availability and continuity can be obtained. SBAS is designed to improve GNSS system integrity and accuracy for aircraft navigation and landing, while an alternative approach to GNSS augmentation is to transmit integrity and differential correction messages from ground-based augmentation systems (GBAS). In addition to existing space and ground based augmentation systems, GNSS augmentation may take the form of additional information being provided by other on-board avionics systems, such as in ABAS. As these on-board systems normally operate via separate principles than GNSS, they are not subject to the same sources of error or interference. Using suitable data link and data processing technologies on the ground, a certified ABAS capability could be a core element of a future GNSS Space-Ground-Aircraft Augmentation Network (SGAAN). Although current augmentation systems can provide significant improvement of GNSS navigation performance, a properly designed and flight-certified SGAAN could play a key role in trusted autonomous system and cyber-physical system applications such as UAS Sense-and-Avoid (SAA)

Think Again – Supplying War: Reappraising Military Logistics and Its Centrality to Strategy and War

This article argues that logistics constrains strategic opportunity while itself being heavily circumscribed by strategic and operational planning. With the academic literature all but ignoring the centrality of logistics to strategy and war, this article argues for a reappraisal of the critical role of military logistics, and posits that the study and conduct of war and strategy are incomplete at best or false at worst when they ignore this crucial component of the art of war. The article conceptualises the logistics–strategy nexus in a novel way, explores its contemporary manifestation in an age of uncertainty, and applies it to a detailed case study of UK operations in Iraq and Afghanistan since 2001

Usual Primary Care Provider Characteristics of a Patient-Centered Medical Home and Mental Health Service Use

BACKGROUND: The benefits of the patient-centered medical home (PCMH) over and above that of a usual source of medical care have yet to be determined, particularly for adults with mental health disorders. OBJECTIVE: To examine qualities of a usual provider that align with PCMH goals of access, comprehensiveness, and patient-centered care, and to determine whether PCMH qualities in a usual provider are associated with the use of mental health services (MHS). DESIGN: Using national data from the Medical Expenditure Panel Survey, we conducted a lagged cross-sectional study of MHS use subsequent to participant reports of psychological distress and usual provider and practice characteristics. PARTICIPANTS: A total of 2,358 adults, aged 18–64 years, met the criteria for serious psychological distress and reported on their usual provider and practice characteristics. MAIN MEASURES: We defined “usual provider” as a primary care provider/practice, and “PCMH provider” as a usual provider that delivered accessible, comprehensive, patient-centered care as determined by patient self-reporting. The dependent variable, MHS, included self-reported mental health visits to a primary care provider or mental health specialist, counseling, and psychiatric medication treatment over a period of 1 year. RESULTS: Participants with a usual provider were significantly more likely than those with no usual provider to have experienced a primary care mental health visit (marginal effect [ME] = 8.5, 95 % CI = 3.2–13.8) and to have received psychiatric medication (ME = 15.5, 95 % CI = 9.4–21.5). Participants with a PCMH were additionally more likely than those with no usual provider to visit a mental health specialist (ME = 7.6, 95 % CI = 0.7–14.4) and receive mental health counseling (ME = 8.5, 95 % CI = 1.5–15.6). Among those who reported having had any type of mental health visit, participants with a PCMH were more likely to have received mental health counseling than those with only a usual provider (ME = 10.0, 95 % CI = 1.0–19.0). CONCLUSIONS: Access to a usual provider is associated with increased receipt of needed MHS. Patients who have a usual provider with PCMH qualities are more likely to receive mental health counseling