Trustee: Full Privacy Preserving Vickrey Auction on top of Ethereum

The wide deployment of tokens for digital assets on top of Ethereum implies the need for powerful trading platforms. Vickrey auctions have been known to determine the real market price of items as bidders are motivated to submit their own monetary valuations without leaking their information to the competitors. Recent constructions have utilized various cryptographic protocols such as ZKP and MPC, however, these approaches either are partially privacy-preserving or require complex computations with several rounds. In this paper, we overcome these limits by presenting Trustee as a Vickrey auction on Ethereum which fully preserves bids' privacy at relatively much lower fees. Trustee consists of three components: a front-end smart contract deployed on Ethereum, an Intel SGX enclave, and a relay to redirect messages between them. Initially, the enclave generates an Ethereum account and ECDH key-pair. Subsequently, the relay publishes the account's address and ECDH public key on the smart contract. As a prerequisite, bidders are encouraged to verify the authenticity and security of Trustee by using the SGX remote attestation service. To participate in the auction, bidders utilize the ECDH public key to encrypt their bids and submit them to the smart contract. Once the bidding interval is closed, the relay retrieves the encrypted bids and feeds them to the enclave that autonomously generates a signed transaction indicating the auction winner. Finally, the relay submits the transaction to the smart contract which verifies the transaction's authenticity and the parameters' consistency before accepting the claimed auction winner. As part of our contributions, we have made a prototype for Trustee available on Github for the community to review and inspect it. Additionally, we analyze the security features of Trustee and report on the transactions' gas cost incurred on Trustee smart contract.Comment: Presented at Financial Cryptography and Data Security 2019, 3rd Workshop on Trusted Smart Contract

An optimization of on-line monitoring of simple linear and polynomial quality functions

This research aims to introduce a number of contributions for enhancing the statistical performance of some of Phase II linear and polynomial profile monitoring techniques. For linear profiles the idea of variable sampling size (VSS) and variable sampling interval (VSI) have been extended from multivariate control charts to the profile monitoring framework to enhance the power of the traditional T^2 chart in detecting shifts in linear quality models. Finding the optimal settings of the proposed schemes has been formulated as an optimization problem solved by using a Genetic Approach (GA). Here the average time to signal (ATS) and the average run length (ARL) are regarded as the objective functions, and ATS and ARL approximations, based on Markov Chain Principals, are extended and modified to capture the special structure of the profile monitoring. Furthermore,the performances of the proposed control schemes are compared with their fixed sampling counterparts for different shift levels in the parameters. The extensive comparison studies reveal the potentials of the proposed schemes in enhancing the performance of T^2 control chart when a process yields a simple linear profile. For polynomial profiles, where the linear regression model is not sufficient, the relationship between the parameters of the original and orthogonal polynomial quality profiles is considered and utilized to enhance the power of the orthogonal polynomial method (EWMA4). The problem of finding the optimal set of explanatory variable minimizing the average run length is described by a mathematical model and solved using the Genetic Approach. In the case that the shift in the second or the third parameter is the only shift of interest, the simulation results show a significant reduction in the mean of the run length distribution of the EWMA4 technique

Evaluation of Flexibility, Microstructure and Elemental Analysis of Some Contemporary Nickel-Titanium Rotary Instruments

BACKGROUND: Contemporary nickel-titanium (NiTi) rotary endodontic instruments had a revolutionary impact on the success of root canal treatment. AIM: To evaluate the flexibility, microstructure and elemental analysis of four different recent NiTi rotary instruments, namely; Wave One Gold, TF adaptive, HyFlex EDM and Gr_Reciproc Blue compared to conventional Protaper Universal (F2). MATERIAL AND METHODS: The NiTi rotary files were subjected to cantilever bending test to evaluate their flexibility. The microstructural characteristics and elemental analysis were examined via scanning electron microscopy (SEM) and energy dispersive X-ray spectrometer (EDX). RESULTS: The TF adaptive, HyFlex EDM and Wave One Gold endodontic files showed significantly lower cantilever bending values (i.e., higher flexibility) than Protaper F2 and Gr_Reciproc Blue (p < 0.05). The SEM micrographs showed that the bulk of all examined files showed multiple striations due to the cutting process, on the other hand, their external surfaces were different: The Protaper Universal F2 showed multiple voids, while the TF Adaptive surface exhibited more uniform structure. The Hyflex EDM had a crater-like surface, whereas Wave one Gold showed machining grooves with minimum defects, while Reciproc Blue displayed machining grooves with random scratch lines. There was a significant difference in bulk and surface elemental analysis of the various examined files, yet composed mainly of the same elements. CONCLUSION: Chemical composition, heat treatment, manufacturing process and geometrical design of the NiTi rotary instrument have a great influence on their flexibility and microstructure

STR-976: EFFECT OF HORIZONTAL REINFORCEMENT ANCHORAGE END DETAIL ON SEISMIC PERFORMANCE OF REINFORCED MASONRY SHEAR WALLS

The most recent design codes for masonry structures necessitate the use of reinforced masonry (RM) shear walls in medium and high seismic areas. There are several factors that control the contribution of the horizontal reinforcement to the in-plane shear capacity of RM shear walls. One of these factors is its anchorage end detail. The current version of the Canadian Standards Association CSA S304-14 for design of masonry structures requires that the anchorage of the horizontal reinforcing bars in the plastic hinge region shall have a 90° or more standard hook at the ends of the wall. However, a 180° standard hook is required for ductile shear walls. On the other hand, some masonry design codes (e.g. New Zealand, NZS 4230:2004) permits a 90° anchorage hook for ductile walls. This paper discusses the results of three identical RM shear walls that were tested under in-plane axial compressive stress and cyclic lateral excitations. All the walls were dominated by shear failure before reaching their flexure capacity. Wall W-180° was constructed with a 180° hook while walls W-90° and W-Str had a 90° hook and straight bar. The test results show that a 180° hook is the most effective anchorage end detail in terms of lateral force capacity and ductility. However, wall W-Str reached a lateral resistance, Que, of 398 kN compared to 412 kN and 418 kN for walls W-90° and W-180°, respectively, with less than 5% difference. Moreover, wall W-180° achieved a high level of displacement ductility of 4.2 instead of 3.9 and 3.6 when using a 90° hook and straight bar at a drop in wall capacity to 80% of Que. More results are analyzed and presented in this paper according to force-based, displacement-based, and performance-based seismic design considerations

STR-975: EFFECT OF SHEAR SPAN TO DEPTH RATIO ON SEISMIC PERFORMANCE OF REINFORCED MASONRY SHEAR WALLS

Over the past few decades there has been a substantial increase in the number of multi-story buildings constructed with reinforced masonry (RM). Similar to reinforced concrete (RC) buildings, shear walls are a popular lateral load resisting system in regions of high seismic activity due to its capability to provide lateral stiffness, strength and energy dissipation. One of the parameters that affects the inelastic behaviour and ductility of RM shear walls is the shear span to depth ratio, M/Vdv. This paper experimentally investigates the effect of M/Vdv on the seismic performance of RM shear walls that are dominated by diagonal shear failure. The experimental work involves two identical full-scale fully grouted rectangular RM shear walls, W-M/Vdv1.2 and W-M/Vdv1.8, tested under in-plane axial compressive stress and cyclic lateral excitations. Wall W-M/Vdv1.8 was subjected to a top moment so that M/Vdv was equal to 1.875, as compared to a value of 1.25 for wall W-M/Vdv1.2 that was tested without a top moment. Most of the existing design equations for nominal in-plane shear strength, Vn, for RM shear walls, including the current provisions of the Canadian Standards CSA S304-14, the Masonry Standards Joint Committee MSJC (2013), and the New Zealand code (2004) for masonry structures, limit the effect of the M/Vdv to an upper value of 1.0. The test results show a significant reduction of 25% in the shear strength when M/Vdv is increased, which means that limiting the effect of M/Vdv to an upper value of 1.0 is overestimating the Vn of RM shear walls at high values of M/Vdv. However, W-M/Vdv1.8 was able to achieve higher levels of displacement ductility. More results were analyzed and are presented in this paper according to force-based, displacement-based, and performance-based seismic design considerations

Transitional Adaptation model for facilitating technology and expertise mobilisation in Gulf AEC Organisations

The fragmented nature of the Architecture, Engineering, and Construction (AEC) industry is well recognised, the main issues of which relate to failures in communication, process, productivity and interoperability. These failures have contributed to an increased proliferation of adversarial relationships between the different parties involved in projects, the result of which have deleteriously affected projects. Challenges include a range of issues, from the veracity of design information throughout the project lifecycle, through to supply chain communication. These are global issues. For example, in the Gulf States, the nature and complexity of AEC projects has changed significantly due to increased globalisation and the emergence of enmeshed transnational practices. This has created an overwhelming reliance on the mobilisation and transfer of technology/expertise of professional expatriates, which has influenced the approach taken to traditional design and construction business models, including staff roles and procedures. New knowledge and ways of working are needed to support future projects in the Gulf States. There is also a requirement to capture and codify domain-specific expertise. This paper discusses the need to enhance Qatar’s AEC industry by fostering a smooth transition from its current position, into a more sustainable [replicable] state. The philosophical underpinnings of this paper take into account disparate socio-cultural, environmental and economic impacts of change, in terms of business models, technology, innovation, labour market needs, local laws/bylaws, and legislation. A theoretical growth model is presented for discussion. This builds on the experience of the UK (in particular) in terms of facilitating the mobility and penetration of technology/expertise/change in the AEC sectors. This paper presents a series of recommendations needed to develop a Pervasive Transnational Adaptation model for Qatar and the Gulf States, covering such issues as: ICT adoption, agile project management, technology-transfer, innovation, offsite construction, Public Private Partnerships, capacity building, and international strategic alliances

Paediatricians’ referral preference of patients with embolised intravascular foreign bodies: a survey-based study

Background: Central line insertion is a routine procedure in medical practice. Dislodgement of lines into the vascular system is a rare complication. We noticed that paediatric health care providers (PHCP) contact the cardiac or general paediatric surgeon for extraction of dislodged lines more frequently than using the less invasive percutaneous approach.Aim: To study the referral preference of PHCP for patient with embolised intravascular foreign bodies.Methods: A questionnaire with three questions was distributed to PHCP of all paediatric subspecialties, including surgery, in two tertiary care centres. The questions were about the total number of patients seen with central line, experience with complications, and preferred specialty for removal of dislodged central lines.Results: The questionnaire was distributed to 128 professionals. The response rate was 79% (n101). Incomplete answers (n14) were excluded. The grades of responders were senior consultants 18%, junior consultants 38%, and residents 43%. Thirty nine percent of care providers experienced dislodgement or fragmentation of central lines. The majority (82%) prefer to refer the patients for surgical removal. Conclusions: Most PHCP in the selected hospitals prefer to refer patients with embolised foreign bodies in the vascular system for surgical removal. The local health policy should be updated for the use of the alternative percutaneous approach.Keywords: cardiac surgery; clinical practice; transcatheter retrieva

High prevalence rate of left superior vena cava determined by echocardiography in patients with congenital heart disease in Saudi Arabia

Background: Persistent left superior vena cava (LSVC) is one of the common anomalies of the systemic veins. Its prevalence is 0.10.3% in the general population and is more common with congenital heart disease (CHD). The importance of detecting persistent LSVC prior to cardiac surgery is paramount for systemic veins cannulations.Aim: The aim was to evaluate the prevalence of persistent LSVC in patients with CHD in Saudi Arabia.Methods: All patients referred to our institution had echocardiography. All complete studies were reviewed for the presence of persistent LSVC. A computerized database was created including the demographic data, CHD diagnoses, and the presence of persistent LSVC.Results: A total of 2,042 were examined with an age range of 1 day to 16 years. The complete echocardiographic studies were 1,832 (90%) of whom 738 (40%) patients had CHD. The prevalence of persistent LSVC in patients with CHD was 7.8% (OR 9.26, 95% CI 4.718.2, pB0.001). The most common cardiac defect associated with persistent LSVC was complete atrioventricular septal defect (AVSD); all patients with AVSD had Down syndrome. The total number of patients with AVSD was 41, and persistent LSVC was found in 11 (26%) of them (odds ratio 5.1, 95% CI 2.410.8, pB0.001).Conclusions: The prevalence of persistent LSVC in the current population is almost double the reported prevalence obtained using the same echocardiographic screening tool.Keywords: left superior vena cava; Down syndrome; atrioventricular septal defect; congenital heart diseas

Optimal Sizing of Fixed Capacitor Banks Placed on a Distorted Interconnected Distribution Networks by Genetic Algorithms

In this paper, the optimal sizing of fixed capacitor banks problem in a distorted interconnected distribution system is formulated and solved by a Genetic Algorithm (GA) solution technique to minimize the cost of power production and capacitor banks under the constraints include voltage limits , sizes of installed capacitors and Total Harmonic Distortion (THD), the algorithm is applied on IEEE 30-bus test system and the results are given for different cases: Light and heavy harmonic cases. Computer simulation shows that the harmonic components affect the optimal capacitor sizing