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Nowadays, blockchain has become increasingly popular due to its promise of supporting critical business services in various areas. Blockchain systems, like Ethereum and Hyperledger Fabric, rely on sophisticated middleware, which enables the execution of smart contracts. Smart contracts define the business logic within cooperative applications. Detecting attacks and vulnerabilities within blockchain is a crucial issue for ensuring the security of different generations of blockchains. Testing a blockchain application serves multiple purposes: it ensures its quality, maximizes test coverage, and minimizes the risks associated with insufficient knowledge that could potentially impact the software development process. That is why several static analysis tools targeting Ethereum smart contracts and Hyperledger Fabric chaincode have recently been proposed by the blockchain research community. However, the efficiency of these analysis tools remains an open issue that requires further investigation. In this context, this paper presents a new taxonomy related to attacks targeting different generations of blockchain and evaluates the available analysis tools that can be utilized to assess the resilience of blockchain 2.0 and blockchain 3.0 against a range of vulnerabilities and attacks. Additionally, this study presents two quantitative analyses: one assessing the performance of tools in evaluating smart contract vulnerabilities within blockchain 2.0, and another analyzing the performance of tools in assessing blockchain 3.0 vulnerabilities within chaincode. Furthermore, this comprehensive study holds value for the research community as it considers various generations of blockchain. [ABSTRACT FROM AUTHOR]

Introduction/purpose: This work provides a comprehensive overview of blockchain technology, elucidating its foundational principles and how it ensures transparency, immutability, and decentralization. The integration of Solidity with blockchain is explored through theoretical approach. Methods: This work meticulously dissects blockchain principles, elucidating transparency, immutability, and decentralization, while exploring Solidity integration in a theoretical framework, ensuring a comprehensive understanding of their intricate relationship and contributing to a broader comprehension of modern distributed ledger technology. Results: The resulting product of this paper will be getting useful knowledge about the technology that practically shapes the world. Conclusion: In conclusion, the adoption of Solidity as a programming language in blockchain technology has proven to be pivotal, enhancing smart contract functionality and overall system security. Its specialized features make it an indispensable tool for developers navigating the complexities of decentralized applications. [ABSTRACT FROM AUTHOR]

Existing smart contract defect prediction methods are not aware of the impact of the internal structure of contracts on defects prediction. To fill this gap, this paper proposed a novel solidity smart contract defect prediction method based on a network metric suite. First, the abstract syntax tree（AST） of the solidity smart contract is constructed using the solidity-antlr4 tool. Second, a contract network is built based on the AST, with nodes representing functions and attributes, and edges representing the function-call relationship between functions and the operation relationship between functions and attributes. Then, it introduced the theory in the field of complex networks to build a network metric suite for Solidity smart contracts. Finally, multiple regression and classification models are used to build smart contract defect prediction models, with different metric suites being features. Comparative results show that defect prediction models trained on combined metric suites including the network metric suite outperform corresponding models without the network metric suite. [ABSTRACT FROM AUTHOR]

Blockchain systems have seen vast growth due to the immense potential in developing secure applications for education, healthcare, and so forth. The healthcare system is extensively researched to provide convenience to human life. With the exponential growth in healthcare systems and devices, patient data security and privacy issues are becoming primary concerns. Blockchain is emerging as a solution to secure healthcare records, but it faces certain shortcomings like transaction time, execution time, gas cost consumption, bandwidth utilization, and so forth. The current article designed an extensive blockchain‐based healthcare system (MyEasyHealthcare) with reduced gas consumption, transaction cost, execution cost, and bandwidth utilization, along with enhanced security at three levels. At the first level, the professionals and patients get registered, which provides identity access management. Secondly, authorization is required for each registered entity by the owners. Lastly, the third level includes a doctor‐patient relationship where the hospital's owner assigns a patient to a particular doctor. The data is protected from the outer world and is preserved only between the doctor and the patient. Moreover, to include the majority of tasks for hospital management, the developed system incorporates a smart contract to record seven different parameters for patient diagnosis by a physician and 15 different parameters by a pathologist. The designed system is evaluated for the amount of gas consumed, transaction cost, execution cost, and bandwidth utilization by simulating/executing the written smart contract on InterPlanetary File System (IPFS) and Remix to check the feasibility of the developed system (MyEasyHealthcare) for the real world; the results testify the proposed system is useful in the real world. [ABSTRACT FROM AUTHOR]

Physical objects behave following the principle of solidity: One solid object cannot pass through another. To what extent does the visual system integrate this physical regularity as a prior constraint? A new variant of the Pulfrich effect demonstrates a surprising degree of tolerance for violations of solidity when pitted against motion and depth cues. When adult participants view a pendulum swinging in the fronto-parallel plane with both eyes (one of which was covered by a light-attenuating filter), they falsely perceive the pendulum as swinging in an elliptical path (known as the "Pulfrich effect"). Here, we show that even when the pendulum's motion takes place entirely behind a solid horizontal bar, observers nevertheless see the pendulum pass through the bar while moving in an ellipse. This illusion suggests that the Pulfrich effect and the underlying stereoscopic depth cues can be robust to object solidity. [ABSTRACT FROM AUTHOR]

We compare medium and high fidelity numerical simulations to experiments conducted on low Reynolds number rotors typical of small scale Unmanned Aircraft Systems (UAS). We first show that these numerical approaches provide reasonable estimates of the aerodynamic performance and farfield tonal noise and hence apply them for the investigation of the influence of solidity ratio on the aerodynamics and acoustics of small scale rotors operating under hovering, iso-thrust conditions. We show that while solidity ratio has a weak impact on aerodynamic performance, it may help drastically reduce farfield tonal noise. This reduction is however found to depend on the interplay between thickness and loading noise such that increasing the solidity by increasing the number of blades at constant blades' aspect ratio or by decreasing the blades' aspect ratio keeping the number of blades constant may yield very different, sometimes opposite, trends. [ABSTRACT FROM AUTHOR]

Hydropower is an important source of energy in Latin America. Many countries in the region, including Brazil, Peru, Colombia, and Chile, rely heavily on hydropower plants to meet their energy needs. However, there are also challenges related to the use of hydropower in the region, such as the construction of dams that can have negative impacts on ecosystems and local communities. A new alternative is the production of energy through hydrokinetic turbines because they are a clean and renewable energy source that does not emit greenhouse gases. In addition, its production is predictable and can be generated in a variety of environments, from coasts to rivers and canals. Within the hydrokinetic turbines are the H-Darrieus turbines although they are still under development, they are seen as an important opportunity to diversify the energy matrix and reduce dependence on fossil fuels. The main purpose of this study is to determine and compare the efficiency of three Darrieus H-type vertical axis hydrokinetic turbines numerically. The turbines were configured with different solidities. The NACA 0018 profile was used for the turbine design. The study was carried out using the ANSYS® Fluent 2022R2 software, two-dimensional (2D) simulations set up constant operating conditions. Rotation speed variations have been set between 21 and 74 RPM with 10 rpm increments. Furthermore, the General Richardson extrapolation method is used for the analysis of mesh convergence, monitoring the turbine power coefficient as a convergence parameter. The numerical results show that the turbine H-Darrieus with a solidity of 1.0, a wider operating range, and lower power and torque coefficient. At low TRS, the largest solidity provided the best efficiency and the greatest self-starting capability, but it also had the smallest operating range. [ABSTRACT FROM AUTHOR]

An Aadhaar is a unique number issued to every citizen in India. Aadhar's current identity authentication relies on the central identities data repository (CDIR) of the unique identification authority of India (UIDAI), which is at risk of a single-point fault attack. Perhaps worse, internal attacks can tamper with the sensitive data of authenticated devices without being detected. In this paper, the proposed system utilizes emerging technology: blockchain for solving the issue of centralized authentication. The proposed system provides a distributed, secure, and tamper-proof ledger platform for Aadhar in that Aadhar is implemented using blockchain ethereum technology. The proposed system considers the unique Aadhar identification (ID) for each citizen of India and registered it on the smart contract of ethereum so that this unique ID may be authenticated by each other in a peer-to-peer network without a central authority. For securing the data, the proposed framework uses hashing technique for significant data (i.e. firmware). Blockchain stores hashed data and instantly any change in the state of the data may be possible to detect. [ABSTRACT FROM AUTHOR]

The new energy scenario is rising a strong interest towards the distributed production from renewable sources; among them, wind seems to be one of the most interesting and at the same time critical due to the challenges of the conversion technology. Operation of small wind energy conversion systems is generally very complex due the extremely variable regime of operation and the high turbulent wind, so that a deep knowledge of the dynamic response of such devices is crucial not only for optimising their performances but also to make them comfortable to be used in residential areas. For these reasons, the present work is focused on analysing the effect in changing the number of blades on a small horizontal axis wind turbine through an experimental campaign in the wind tunnel. The turbine dynamics has been characterised running some "wind ramp" tests and analysing the rotor capability in following the wind as well the vibrations transmitted by the turbine during the operation. Results demonstrate that a higher number of blades, despite a small decrease of performance, can make the machine more efficient in operating at low wind regimes. At the same time, a higher number of blades can make the rotor efficient even at lower speed of rotation, thus limiting the risks of having high magnitude vibrations. [ABSTRACT FROM AUTHOR]

Recent development in using wind turbines for urban areas results in inserting turbines inside buildings. As buildings' walls may act as a duct for the turbine, this study focuses on a ducted wind turbine with a fixed duct geometry. A method is organized for achieving the improved generated power and the wind speed augmentation with fixed geometry of duct regardless of the type of the turbine, which is the aim of building designers. Using a porous disc (PD) instead of a wind turbine rotor makes the study cost and time effective. PDs within a duct help estimate any given duct's maximum available power extraction capability. In addition, experimental and numerical tests examine the effect of PDs solidity on the performance of diffuser augmented wind turbines and the corresponding economic analysis. Both experimental and numerical results agree that the power coefficient highly depends on the solidities of the PD. The power coefficient of a ducted PD with a solidity of 0.3 is augmented by up to 30%. Nevertheless, in some cases, employing a duct can contribute to the power reduction if the solidity exceeds a critical value. A smoke visualization technique helps vortex study. Economic assessment of a ducted turbine for three scenarios belonging to Germany and Italy shows a 15.3% decline in cost per electricity production. The payback period decreases by 3.42 years, 7.68 months, and 6.36 months for Scenarios 1, 2, and 3. [ABSTRACT FROM AUTHOR]

In this study, small horizontal-axis wind turbine blades operating at low wind speeds were optimized. An optimized blade design method based on blade element momentum (BEM) theory was used. The rotor radius of 0.2 m, 0.4 m, and 0.6 m and blade geometry with single (W1 & W2) and multistage rotor (W3) were examined. MATLAB and XFoil programs were used to implement to BEM theory and devise a six novel airfoil (NAF-Series) suitable for application of small horizontal axis wind turbines at low Reynolds number. The experimental blades were developed using the 3D printing additive manufacturing technique. The new airfoils such as NAF3929, NAF4420, NAF4423, NAF4923, NAF4924, and NAF5024 were investigated using XFoil software at Reynolds numbers of 100,000. The investigation range included tip speed ratios from 3 to 10 and angle of attacks from 2° to 20°. These parameters were varied in MATLAB and XFoil software for optimization and investigation of the power coefficient, lift coefficient, drag coefficient, and lift-to-drag ratio. The cut-in wind velocity of the single and multistage rotors was approximately 2.5 and 3 m/s, respectively. The optimized tip speed ratio, axial displacement, and angle of attack were 5.5, 0.08m, and 6°, respectively. The proposed NAF-Series airfoil blades exhibited higher aerodynamic performances and maximum output power than those with the base SG6043 and NACA4415 airfoils at low Reynolds number. [ABSTRACT FROM AUTHOR]

In this research work, the investigation and optimization of small horizontal axis wind turbine blade at low wind speed are pursued. The experimental blades were developed using the 3D printing additive manufacturing technique. The airfoils E210, NACA2412, S1223, SG6043, E216, NACA4415, SD7080, SD7033, S1210, and MAF were tested at the wind speed of 2–6 m/s. The airfoils and optimum blade geometry were investigated with the aid of the Xfoil software at Reynolds number of 100,000. The initial investigation range included tip speed ratios from 3 to 10, solidity from 0.0431–0.1181 and angle of attacks from 2o to 20o . Later on, these parameters were varied in MATLAB and Xfoil software for optimization and investigation of the power coefficient, lift coefficient, drag coefficient, and lift to drag ratio. The cut-in wind speed of the rotors was 2 and 2.5 m/s with the winglet-equipped blades and without winglets. It was found that the E210, SG6043, E216 NACA4415, and MAF airfoil displayed better performance than the NACA 2412, S1223, SD7080, S1210, and SD7003 for the geometry optimized for the operating conditions and manufacturing method described. [ABSTRACT FROM AUTHOR]

Physical reasoning appears central to understanding how the world works, suggesting adaptive function across the animal kingdom. However, conclusive evidence for inferential reasoning about physical objects is limited to primates. We systematically tested a central feature—understanding of solidity—in domestic dogs, by adapting a validated procedure (the shelf task) previously used to test children and non-human primates. Dogs watched a treat dropped into an apparatus with a shelf either present (treat landing on the shelf) or absent (treat landing on the bottom surface) and chose where to search for it (above or below the shelf). Across four studies (n = 64), we manipulated visual access to the treat trajectory and apparatus interior. Dogs correctly inferred the location of treats using physical cues when the shelf was present (Study 1), and learned rapidly when visual cues of continuity were limited (Study 2), and when the shelf was absent (Study 3). Dogs were at chance when the apparatus was fully occluded, and the presence and absence of the shelf varied across trials within subjects, and showed no evidence of learning (Study 4). The findings of these four studies suggest that dogs may be able to make some inferences using solidity and continuity and do not exhibit proximity or gravity biases. However, dogs did not always search correctly from Trial 1, and failed to search correctly when the rewarded location varied within-subjects, suggesting a role for learning, and possible limits to their ability to make inferences about physical objects. [ABSTRACT FROM AUTHOR]

When a hydrokinetic turbine operates in a confined flow, blockage effects are introduced, altering the flow at and downstream of the rotor. Blockage effects have a significant effect on the loading and performance of turbines. As a result, understanding them is critical for hydrokinetic turbine design and performance prediction. The current study examines the main and interaction effects of solidity (σ), tip speed ratio (TSR), blockage ratio (ε), and pitch angle (θ) on how the blockage influences the performance (CP) of a three-bladed, untwisted, untapered horizontal axis hydrokinetic turbine. The investigation is based on validated 3D computational fluid dynamics (CFD), design of experiments (DOE), and the analysis of variance (ANOVA) approaches. A total number of 36 CFD models were developed and meshed. A total of 108 CFD cases were performed as part of the analysis. Results indicated that the effect of varying θ was only noticeable at the high TSR. Additionally, the rate of increment of CP with respect to ε was found proportional to both TSR and σ. The power and thrust coefficients were affected the most by σ , followed by ε, TSR, and then θ. [ABSTRACT FROM AUTHOR]

Modern thinking about the ground tends to take it as a purely material base for the unfolding of history and ideas emerging on its surface. In this article, I question above-ground visions of city building by drawing on both the history of ground engineering and ethnographic fieldwork carried out in Paris with geotechnicians. I address the difficulties that theorists have faced over past centuries in modelling soils, and the contemporary practice of building piles underneath buildings to anchor them. From this unfolds an understanding of the ground as produced through an equilibrium between forces and materials in which buildings become participants, rather than a solid base upon which they stand. Looking at the activities of foundation builders, we find that the inertia of the urban soil no longer betokens an absence of activity or movement, but is rather a continuous achievement, a slow and dangerous process of balancing tensions. [ABSTRACT FROM AUTHOR]

This issue opens an inquiry into the tension between solidity and fluidity. This tension is ingrained in the Western intellectual tradition and informs theoretical debates across the sciences and humanities. In physics, solid is one phase of matter, alongside liquid, gas and plasma. This, however, assumes all matter to be particulate. Reversing the relation between statics and dynamics, we argue to the contrary, that matter exists as continuous flux. It is both solid and fluid. What difference would it make were we to start from our inescapable participation in a world of solid fluids? Is solid fluidity a condition of being in the midst of things, or of intermediacy on a solid-fluid continuum? Does the world appear fluid in the process of its formation, but solid when you look back on things already formed? Here we open new paths for theorizing matter and meaning at a time of ecological crisis. [ABSTRACT FROM AUTHOR]

Zygmunt Bauman addressed spatiotemporal compression as a critical aspect of the transition from solid to liquid modernity. In this transition, speed and flexibility came to define the conditions of social life which no longer relied on spatiotemporal separation as the basis of all power relations. But digitization of these conditions raises the question of whether the present phase of modernity depicts a resolidification of capital and power that exploits the fluidity of a densely intermediated world. By treating databases as the new localities of power, the digital operations inherent to their utility and productivity render the systemic nature of intermediation as solid as the power relations of the pre-digital era. The example of mass surveillance demonstrates the solidity of a new power derived from surreptitious data gathering and collation in populations attuned to intermediation as a way of life. A new mass culture is emerging through spaces of power that have reset speed in the service of datafication. This is not simply a culture of mobility and choice but one prefabricated and utilized for advancing the redesigned solidity of a digitized modernity. [ABSTRACT FROM AUTHOR]

Hydrokinetic turbine provides a viable option for tapping energy from free-flowing water, making it an attractive contributor to the renewable power landscape. This study investigates the effects of blade number and solidity on the performance and wake recovery of a small-scale vertical axis helical hydrokinetic turbine under different tip speed ratios and inflow velocities. Computational fluid dynamics simulations are employed, followed by experimental validation, to analyze power, self-start, torque pulsations, velocity deficit and flow field characteristics. The highest power coefficient is found to be 0.24 for a 4-bladed rotor with 0.3 solidity at a tip speed ratio of 1.0 and inflow velocity of 1.0 m/s. The performance of the studied rotors decreases as inflow velocity increases due to high turbulence experienced, resulting in flow separation. The self-start characteristics are shown to improve with solidity, while torque pulsations are greatly diminished with the increase in number of blades. The wake analysis results show that the velocity deficit and turbulence intensity increase significantly as the number of blades increases. Moreover, the time-averaged streamwise velocity values are observed to reach almost 95 % at a downstream distance of 19–25 times the rotor diameter for investigated rotors. [Display omitted] • Impact of number of blades on VAHHT rotor performance and wake recovery is explored. • CFD results are validated with the experimental data. • Highest power coefficient is found to be 0.24 for a 4-bladed rotor with 0.3 solidity. • Velocity deficit in wake increased significantly as the blade number increased. • Wake recovery distance is accomplished at 19-25D for investigated rotors. [ABSTRACT FROM AUTHOR]

Ethereum is the most widely used open-source public chain project, with smart contracts serving as the pattern for developing decentralized applications. The prevalence of attacks against smart contracts has increased in recent years due to the attached amounts of high-value cryptocurrency. Various attacks against smart contracts have caused significant financial losses, amounting to hundreds of millions of dollars. As manual auditing of smart contracts is time-consuming and costly, automatic detection of vulnerabilities is crucial. Existing work does not dig deeper into contextual information contained in the program, which suffers from the difficulty of covering paths with more complex conditions. In this paper, we propose Ethchecker, a smart contract vulnerability detection tool which combines fuzzing and symbolic execution techniques together. Particularly, we propose an analysis module to extract static information from smart contracts. Besides, the tool introduces a genetic algorithm to enlarge code coverage, while considering the contextual information of the code. The results of the experiment show that in terms of F1-score for vulnerability detection, Ethchecker outperforms sFuzz by an average of 21.89% and outperforms Mythril by an average of 12.5%. Furthermore, in the comparison experiments on a dataset consisting of 1000 long smart contract codes (comprising over 3000 instructions), the proposed algorithm can improve the code coverage by 18.56% compared to the random fuzzing algorithm. In addition, we also used Ethchecker to test against 8922 randomly crawled real-world smart contracts. The result demonstrates the stability of this tool. [ABSTRACT FROM AUTHOR]

This paper presents the effect of the number of blades on the aeroacoustic characteristics and aerodynamic performance of propellers utilized in urban air mobility vehicles through an extensive experimental study. A detailed parametric study is conducted for two, three, and five-bladed propellers. Investigations are carried out under static thrust conditions and incoming axial flow velocities for various rotational speeds. The spectra and directivity of the far-field noise are studied in detail for broadband and tonal components. Results show that two-bladed propellers produce higher tonal noise levels than other blade numbers for the same tip speed, while five-bladed propellers produce the highest broadband noise levels. The highest level of noise radiation is noted in the upstream and downstream directions for broadband noise, whereas tonal noise is radiated mainly in the plane of rotation. Results also indicate that high-frequency broadband humps are observed for higher advance ratios, likely caused by the formation of laminar separation bubbles, and that amplitude increases with blade numbers. The results of this study provide valuable insight for further investigations of propeller noise and aerodynamic performance. • 2-bladed propellers consistently exhibit higher tonal noise than those with more blades. • Broadband noise radiation increases with blade number. • High-frequency broadband humps emerge in noise spectra at higher advance ratios. [ABSTRACT FROM AUTHOR]

In our previous work, we proposed a verification framework that shifts from the “code is law” to a new “specification is law” paradigm related to the safe evolution of smart contracts. The framework proposed there relaxed the well-established requirement that, once a smart contract is deployed in a blockchain, its code is expected to be immutable. More flexibly, contracts are allowed to be created and upgraded provided they meet a corresponding formal specification that was fixed. In the current paper, we extend this framework to allow specifications to evolve, provided a refinement notion is preserved. We propose a notion of specification refinement tailored for smart contracts and a methodology for checking it. In addition to weakening preconditions and strengthening postconditions and invariants, we allow for the change of data representation and interface extension. Thus, we are able to reason about a significantly wider class of smart contract evolution histories, when contrasted with the original framework. The new framework is centred around a trusted deployer: an off-chain service that formally verifies and enforces the notions of implementation conformance and specification refinement. We have investigated its applicability to the safe deployment and upgrade of contracts implementing widely used Ethereum standards (the ERC20 Token Standard, the ERC3156 Flash Loans, the ERC1155 Multi Token Standard and The ERC721 standard for Non-Fungible Tokens); we handle evolutions possibly involving changes in data representation and interface extensions. [ABSTRACT FROM AUTHOR]

Smart contracts have rapidly gained popularity as self-contained pieces of code, especially those run on the Ethereum blockchain. On the one hand, smart contracts are immutable, have transparent workings, and execute autonomously. On the other hand, these qualities make it essential to properly test the behavior of a smart contract before deploying it. In this paper, we introduce SolAR , a tool and approach for Sol idity A utomated Test Suite Gene R ation. SolAR allows smart contract developers to generate test suites for Solidity smart contracts optimized automatically for branch coverage using either a state-of-the-art genetic algorithm or a fuzzing approach. It enables a novel way to handle blockchain operations—or ChainOps—from a pipeline perspective, entailing a larger-scale as well as more manageable and maintainable service continuity. [ABSTRACT FROM AUTHOR]

The object of research is software for financial accounting and distribution of funds in a non-profit charitable foundation using smart contracts of the Ethereum platform. The work is aimed at designing and implementing a software application for a charitable foundation, which allows to exclude the misuse of funds of a non-profit charitable foundation. The paper proposes an implementation of the Ethereum smart contract for the software of a charitable foundation. In the app, users can apply for financial aid or make a charitable donation. The request for financial support is confirmed by administrators to avoid abuse by those seeking help. Anyone who has a crypto wallet can become a sponsor by transferring funds from its account to a selected request. The sponsor remains incognito when making a charitable contribution. After collecting the entire declared amount, the funds are automatically transferred to the crypto wallet of the request’s owner. A smart contract and a corresponding decentralized web application for interacting with it were experimentally deployed, and their joint work was tested. To implement the smart contract, the Solidity programming language was chosen; developed smart contract converted to bytecode using remix. The resulting bytecode is ready to be deployed on the Ethereum platform. Decentralized web application for interacting with the contract is implemented using Web3.js, Vue.js. A rough estimate of the cost of deploying a project on the Ethereum platform has been made. The deployment and operation of smart contracts and web applications comes with a certain overhead, which is most dependent on the cost of ether. However, this is a justified price to pay for the transparency of transactions and the shadowing of the turnover of funds of the charitable foundation. The results of the research can be used as a basis for further transformation into full-fledged software with the ability to submit all reporting documents to the relevant government agencies and sponsors. [ABSTRACT FROM AUTHOR]

The existence and development of current and future human society depends on the proper functioning of the banking financial system. The capital and the market, as essential elements of social development, are fully integrated into the global social system and represent the engine of progress. From a systemic perspective, with reference to the concept of critical infrastructure, for the economy and society, the banking financial system is like the circulatory system for a living organism. In this respect, this analysis demonstrates the essential role and necessity of the existence of the banking financial system as a critical infrastructure. [ABSTRACT FROM AUTHOR]

The object of research is software for financial accounting and distribution of funds in a non-profit charitable foundation using smart contracts of the Ethereum platform. The work is aimed at designing and implementing a software application for a charitable foundation, which allows to exclude the misuse of funds of a non-profit charitable foundation. The paper proposes an implementation of the Ethereum smart contract for the software of a charitable foundation. In the app, users can apply for financial aid or make a charitable donation. The request for financial support is confirmed by administrators to avoid abuse by those seeking help. Anyone who has a crypto wallet can become a sponsor by transferring funds from its account to a selected request. The sponsor remains incognito when making a charitable contribution. After collecting the entire declared amount, the funds are automatically transferred to the crypto wallet of the request’s owner. A smart contract and a corresponding decentralized web application for interacting with it were experimentally deployed, and their joint work was tested. To implement the smart contract, the Solidity programming language was chosen; developed smart contract converted to bytecode using remix. The resulting bytecode is ready to be deployed on the Ethereum platform. Decentralized web application for interacting with the contract is implemented using Web3.js, Vue.js. A rough estimate of the cost of deploying a project on the Ethereum platform has been made. The deployment and operation of smart contracts and web applications comes with a certain overhead, which is most dependent on the cost of ether. However, this is a justified price to pay for the transparency of transactions and the shadowing of the turnover of funds of the charitable foundation. The results of the research can be used as a basis for further transformation into full-fledged software with the ability to submit all reporting documents to the relevant government agencies and sponsors. [ABSTRACT FROM AUTHOR]

Light intensity, temperature, and humidity are key factors affecting photosynthesis, respiration, and transpiration. Among these factors, temperature is a crucial parameter to establish an optimal greenhouse climate. Temperature can be controlled by using an appropriate climate screen, which has a considerable impact on crop quantity and quality. The precise measurements of longwave radiative properties of screens are vital to the selection of the most suitable screen for greenhouses so that the desired temperature and a favorable environment can be provided to plants during nighttime. The energy-saving capability of screens can also be calculated by using these properties as inputs in a physical model. Two approaches have been reported so far in the literature for the measurement of these properties, i.e., spectrophotometry and wideband radiometry. In this study, we proposed some modified radiation balance methods for determining the total hemispherical longwave radiative properties of different screens by using wide-band radiometers. The proposed method is applicable to materials having zero porosity, partial opacity, and asymmetric screens with 100% solidity. These materials were not studied previously under natural conditions. The existing and proposed methods were applied and compared, and it was found that the radiometric values obtained from the developed methodology were similar to those previously reported in the literature, whereas the existing method gave unstable results with zero reflectance. [ABSTRACT FROM AUTHOR]

Vertical axis wind turbines (VAWTs) can be suitably installed in urban regions. Although the power performance is essential, the noise generated by a VAWT may influence the living environment. An accurate prediction of power and noise performance is therefore necessary. In the present study, a precise aerodynamic and aeroacoustic performance assessment of a Darrieus VAWT is accomplished with the aim of exploring the effect of solidity parameter using a high-fidelity method. The improved delayed detached eddy simulation (IDDES) and the Ffowcs Williams and Hawkings (FW-H) acoustic analogy approaches have been utilized for predicting flow field and noise level. The simulations were performed in three different solidities at a specific tip speed ratio (TSR). It is shown that changing the solidity parameter affects both power and noise level remarkably. Change in the aerodynamic performance mostly occurs due to variation in instantaneous effective angle of attack which comprises many detailed discussions. The lower the solidity the higher the value of effective angle of attack. The noise level also affects by changing solidity as consequence of flow field variation. It is discussed here how the noise level would alter in terms of solidity, TSR, distance and azimuth angle. As the solidity increases, the sound pressure level (SPL) at blade pass frequency increases. Since design of quieter VAWT with application in urban regions recently is of the most interest and importance therefore such deep studies could appropriately address hybrid criteria and be helpful in future investigations. [ABSTRACT FROM AUTHOR]

The study of sequence spaces and summability theory has been an important aspect in defining new notions of convergence for the sequences that do not converge in the usual sense. Paving the way into the applications of law of large numbers and theory of functions, it has proved to be an essential tool. In this paper we generalise the classical Maddox sequence spaces c 0 (p) , c (p) , ℓ (p) and ℓ ∞ (p) and define new ideal paranormed sequence spaces c 0 I (ϒ r , p) , c I (ϒ r , p) , ℓ ∞ I (ϒ r , p) and ℓ ∞ (ϒ r , p) defined with the aid of Jordan's totient function and a bounded sequence of positive real numbers. We develop isomorphism between certain maps and also find their α-, β- and γ-duals. We examine algebraic and topological properties of these corresponding spaces. Further we study some standard inclusion relations and prove the decomposition theorem. [ABSTRACT FROM AUTHOR]

Although there is an analogy between electrical and thermal conductivities, rock electrical parameters are mostly related to the pore system, whereas thermophysical properties mostly affected by the solid part. It seems that using the mentioned analogy and simultaneous consideration of the electrical and thermophysical properties lead to a better description of the rocks. In this paper, a solid part of rock was considered as a bundle of cylindrical rods. The formation thermal factor (FT) was defined as a parameter based on thermal conductivities of evacuated rock and its solid part and using the analogy with the definition of formation resistivity factor (FR). Also, a combination of electrical and thermophysical properties was used to describe rock permeability. Two datasets of dolomite and sandstone were used to confirm the analogy between FT and FR. Results revealed that there is a power relation between FT and rock solidity similar to the power relationship between FR and porosity, i.e., Archie's equation. Determination coefficients (R2) of FT versus solidity for sandstone and dolomite samples were 0.97 and 0.99, respectively. Furthermore, it was concluded that permeability and FR × FT have a power relationship with high R2 for sandstone (R2 = 0.92) and dolomite samples (R2 = 0.93). Moreover, the relationship between permeability and FR × FT was proven using the Kozeny-Carman model. Finally, the electrical quality index (EQI) and thermal quality index (TQI) were defined based on the analogy with reservoir quality index (RQI). It is believed that simultaneous consideration of RQI, EQI, TQI, FR × FT , and their correlations with well-log data lead to a more accurate characterization of the reservoir rock. [ABSTRACT FROM AUTHOR]

According to today's education system, the content, applicability, quality and performance measurement criteria of the courses may vary according to countries, educational institutions and educators. Because of incorrect performance measurement, hidden skills disappear before they appear. Thanks to the graduation diploma it is observed that people with less professional knowledge and skills come to better places than those who are more knowledgeable and skilled. In addition, due to the lack of a proper training plan and long periods of education for the target learning community, boredom and financial problems may arise. In this study, a blockchainbased lifelong learning platform whose content, processing, reliability, decentralized, open to continuous and rapid accessibility, and evaluation criteria and method is completely objective is proposed while trying to avoid material and temporal problems. Thanks to this platform, the diplomas to be received by the students who have successfully passed the end-of-education exams will be time-stamped, immutable, safe and traceable. At the same time, all these documents, storage of training contents, diplomas, certificates, post-training exams and all related files, will be kept accessible, secure and immutable thanks to IPFS, the Inter Planetary File System. Achievements, employer and employee pools to be created according to the achievements, and recruitment contracts to be realized will be controlled by smart contracts and absolute reliability and objectivity will be ensured. All these concepts will be made available through a decentralized application (DApp) which will run on a private blockchain network that requires a partial permission to be established. [ABSTRACT FROM AUTHOR]

Some classes of real number sequences over n--normed spaces defined by means of Orlicz functions, a bounded sequence of strictly positive real numbers, a multiplier and a normal paranormed sequence space are investigated. Relevant properties of such classes have been investigated. Moreover, relationships among different such classes of sequences have also been studied under various parameters and conditions. Finally, the spaces are investigated for some other useful properties. [ABSTRACT FROM AUTHOR]

Digital Bibliography and Library Project dataset is a collection of bibliographic records of computer science publications of various authors and co-authors. It contains approximately 1.5 million bibliographic records. An algorithm for an author's information retrieval is developed to retrieve details of specific author publications and correlation among authors. Further performance of an author is measured with parameters like consistency, contribution factor, stability, cooperativeness, and solidity. The work presented is tested on the DBLP dataset. Experimental results clearly support the claim that it works efficiently for retrieving specific author-publication records and its analysis with respect to suggested parameters. [ABSTRACT FROM AUTHOR]

The expenses of a wind turbine modeling in particular a wind farm modeling either numerically or experimentally cause to take the advantages of actuator disks (AD). Porous disks (PD) are used to simulate actuator disks in experiments especially for wake studies. A rotor of a wind turbine replaced by a PD can be modeled efficiently with less cost and process time. For a proper PD selection, some semi‐empirical equations are suggested for a range of solidity of 0.2‐0.6. These equations came from a number of tests. The PDs with different dimensions and solidity values were considered for the tests and models. The results of 2D and 3D numerical simulations and the experimental results show that at the solidity of 0.5, the coefficient of performance of a PD reaches approximately 16/27 which is equal to the Betz's limit; the relation between the coefficient of power and the solidity is fitted by a parabolic equation. The average error of the proposed equations for the power coefficient is reported 1.59%. Finally, based on the current results, some semi‐empirical equations are suggested to help the initial PD selection, and then, the cost of further studies may decrease. [ABSTRACT FROM AUTHOR]

The following study proposes the analysis of a Darrieus H-type vertical axis hydrokinetic turbine that can be implemented in regions not interconnected to the Colombian electricity system, especially coastal areas. The objective of the study is to analyze the number of blades in the efficiency of the hydrokinetic turbine, for this, 27 types of rotors are proposed, in which, the number of blades is varied from 2 to 10 for 3 different solidity values. Concluding that from 3 blades the negative torques produced are reduced, increasing the capacity of auto-start, however, when the number of blades increases the total torque generated by the turbine decreases which leads to a decrease in efficiency. [ABSTRACT FROM AUTHOR]

In this work, the influence of thickness and solidity of guide vane on the unsteady flow of a radial inflow turbine with variable nozzle has been numerically studied. Three vanes with the thickness changes from 0.3 to 0.1 and the solidity changes from 1.43 to 2.86, were chosen for this study. By investigating the unsteady flow field, it is found that the vane with low thickness and high solidity (vane B) can reduce shock by 75 % compared to the vane with high thickness and low solidity (base model); meanwhile, it can also mitigate the nozzle endwall leakage flow thus improves the flow uniformity of rotor inlet. As the intensity of shock and nozzle leakage flow were mitigated, the aerodynamic loading fluctuation of rotor blade can be weakened effectively, which will lead to improved rotor blades forced response. However, at small opening, vane B shows about 0.5 % lower efficiency than the base model; at large open condition, the efficiency degradation of vane B is up to 1.4 %. Therefore, there is a trade-off between the efficiency and forced response when choosing the nozzle vane solidity and thickness. [ABSTRACT FROM AUTHOR]

Background: Phosphate is an essential plant macronutrient required to achieve maximum crop yield. Roots are able to uptake soil phosphate from the immediate root area, thus creating a nutrient depletion zone. Many plants are able to exploit phosphate from beyond this root nutrient depletion zone through symbiotic association with Arbuscular Mycorrhizal Fungi (AMF). Here we characterise the relationship between root architecture, AMF association and low phosphate tolerance in strawberries. The contrasting root architecture in the parental strawberry cultivars 'Redgauntlet' and 'Hapil' was studied through a mapping population of 168 progeny. Low phosphate tolerance and AMF association was quantified for each genotype to allow assessment of the phenotypic and genotypic relationships between traits. Results: A "phosphate scavenging" root phenotype where individuals exhibit a high proportion of surface lateral roots was associated with a reduction in root system size across genotypes. A genetic correlation between "root system size" traits was observed with a network of pleiotropic QTL found to represent five "root system size" traits. By contrast, average root diameter and the distribution of roots appeared to be under two discrete methods of genetic control. A total of 18 QTL were associated with plant traits, 4 of which were associated with solidity that explained 46% of the observed variation. Investigations into the relationship between AMF association and root architecture found that a higher root density was associated with greater AMF colonisation across genotypes. However, no phenotypic correlation or genotypic association was found between low phosphate tolerance and the propensity for AMF association, nor root architectural traits when plants are grown under optimal nutrient conditions. Conclusions: Understanding the genetic relationships underpinning phosphate capture can inform the breeding of strawberry varieties with better nutrient use efficiency. Solid root systems were associated with greater AMF colonisation. However, low P-tolerance was not phenotypically or genotypically associated with root architecture traits in strawberry plants. Furthermore, a trade-off was observed between root system size and root architecture type, highlighting the energetic costs associated with a "phosphate scavenging" root architecture. [ABSTRACT FROM AUTHOR]

Large Eddy Simulations (LES) are performed on a Vertical Axis Hydrokinetic Turbine (VAHT) at two different solidities, so as to enable a more complete physical description of the flow than for classic statistical calculations. To analyze the turbine performances, local quantities are defined to evaluate the contribution of the different turbine elements to the global VAHT power coefficient. For a deeper analysis of the major losses, the real turbine is also compared with an ideal turbine composed of only three infinite blades. It is observed that the ideal turbine with the lower solidity provides the best performance, but the losses due to the blade tips and the arms strongly increase for the real turbine at the same solidity. Consequently, for the considered real turbine, there is no clear gain to decrease the solidity. Simulations of the ideal turbine are performed for various solidities at their optimal Tip Speed Ratio (TSR) to study the evolution of optimal power coefficient as a function of solidity. A maximum power coefficient is obtained for a small value of the solidity. This is explained because the optimal TSR of this optimal solidity leads to angles of incidences on the blade which avoid a penalizing dynamic stall phenomenon but are high enough to produce an important positive torque The design of an efficient turbine has then to limit losses, to be able to use small solidity and then to avoid dynamic stall phenomenon by having a high optimal TSR. • LES of VAHT are performed for two different solidities. • Major losses are evaluated by comparison with ideal turbines. • The optimal power coefficient is evaluated as a function of solidity. [ABSTRACT FROM AUTHOR]

Solidity smart contracts play an important role in enabling interactions and collaborations among users in a decentralized blockchain-based community, and their security has received much attention in the industry. One of the most serious security issues faced by Solidity smart contracts is that the use of d e l e g a t e c a l l to make cross-contract calls will tamper with contract privilege, which is difficult to detect. To improve the robustness of smart contract privilege control mechanisms at the level of source code, this paper designs and implements a new cross-contract static analysis tool called TaintGuard based on the abstract syntax tree of Solidity code and by combining taint analysis and instrumentation monitoring. TaintGuard uses solc to obtain the abstract syntax tree of the contract source code and then traverses the nodes of the tree to filter call relations that use d e l e g a t e c a l l for cross-contract calls. Then, TaintGuard obtains the control flow graph within the target function, determines whether there are problematic paths in the control flow graph that may cause implicit leakage of contract privileges through static taint analysis, and instruments monitoring code in the corresponding position of the program. In this way, the contract status in the runtime stage is monitored to prevent the contract privileges from being tampered with by malicious callers. Finally, TaintGuard is evaluated against existing static analysis tools for Solidity smart contracts. The evaluation results indicate that TaintGuard outperforms other tools in terms of execution efficiency. Also, it can effectively fix the contract code with privilege leaks with a acceptable overhead. [ABSTRACT FROM AUTHOR]

Abstract In order to increase the efficiency of straight-bladed vertical axis wind turbine (SB-VAWT), the inboard, outboard, two-side Gurney flap (GF) and dimple-GF are applied in SB-VAWT. The two-dimensional CFD simulation is utilized in this paper. Based on the validation of numerical simulation, the power coefficient, torque coefficient, vorticity field and standard deviation of fluctuation aerodynamic load of SB-VAWT are obtained. The results indicate that all kinds of GF can enhance the power coefficient in a certain range of tip-speed ratio (TSR). Compared to the clean SB-VAWT with solidity of 0.25, the outboard dimple-GF can increase the maximum power coefficient by 17.92% at TSR = 3.1. At all TSR, the two-side dimple-GF can obviously shrink the scale of trailing vortex and decrease the vorticity magnitude of trailing vortex. The outboard GF and dimple-GF can significantly increase the power coefficient of SB-VAWT with the different solidities at low TSR. When the blade number increases, the load fluctuation is reduced and the aerodynamic performance is decreased due to the intense interaction among the trailing edge vortices of multiple blades. A lowest load fluctuation is achieved at the blade number of 5. Highlights • The effect of inboard/outboard/two-side Gurney flap on SB-VAWT is investigated. • The effect of solidity on SB-VAWTs with outboard GF and dimple-GF is illustrated. • A proper simulation validation is carried out by TSST turbulence model. [ABSTRACT FROM AUTHOR]

This note points out a conflict between some common intuitions about metaphysical possibility. On the one hand, it is appealing to deny that there are robust counterfactuals about how various physically impossible substances would interact with the matter that exists at our world. On the other hand, our intuitions about how concepts like MOUNTAIN apply at other metaphysically possible worlds seem to presuppose facts about 'solidity' which cash out in terms of these counterfactuals. I consider several simple attempts to resolve this conflict and note they all fall short. [ABSTRACT FROM AUTHOR]

In this paper we have introduced and investigated the difference triple sequence spaces c3 0 (Δ3), c3(Δ3), c3R(Δ3), lc3 c∞ .(Δ3) and c3B(Δ3) applying the difference operator Δ3, on the triple sequence (xlmn) and studied some of their algebraic and topological properties. We have also proved some inclusion relation involving these sequence spaces. [ABSTRACT FROM AUTHOR]

In this paper we introduce the sequence spaces c0i(Δ) ,ci(Δ) and li ∞ (Δ) of interval numbers and study some of their algebraic and topological properties. Also we investigate some inclusion relations related to these spaces. [ABSTRACT FROM AUTHOR]

Abstract The paper aims at the quantitative characterization of solidification morphologies of plasma sprayed Fe-based amorphous splats. The spraying power was adjusted to provide the particles with different in-flight status. The SprayWatch-2i diagnostics system was employed to measure the real-time velocity and surface temperature of droplets for the estimation of the melting index (M.I.). The mirror polished stainless steel with 250 °C preheating temperature was utilized to collect individual splat. The solidity, flattening degree, as well as other basic geometric parameters of splat were calculated based on the 3D morphology. The spreading mechanism of droplet was discussed at length and the solidification type of splat was classified by the combination of solidity and flattening degree. The results indicate that with the increment of spraying power, the average surface temperature increases remarkably, while the changes in velocity are not so obvious. The molten droplet can spread into three types of splat, namely, disk-like type, flower-like type and fragmented type. The combination of solidity and flattening degree is effective in the characterization of the solidification type of the droplet. Generally, the splats tend to be more irregular and the flattening degree is inclined to be larger under higher spraying power. Highlights • The individual splat of plasma sprayed Fe-based amorphous droplet with different spraying power was obtained. • The melting index was semi quantitatively estimated based on the velocity and surface temperature of in-flight droplet. • The solidity, flattening degree, as well as other basic geometric parameters of splat were calculated. • The solidification type of splat was classified by the combination of solidity and flattening degree. • The influence of droplet melting degree on the spreading and solidification mechanism was discussed. [ABSTRACT FROM AUTHOR]

Abstract The Darrieus vertical axis wind turbine (VAWT) has been the subject of a large number of recent studies to improve self-starting capability and aerodynamic performance. This study presents a computational fluid dynamics simulation of the vertical axis wind turbine with fixed and variable pitch at different solidities. In order to introduce the best efficiency value of solidity for a variable-pitch vertical axis wind turbine, a computational modeling of two-dimensional transient flow around a VAWT at solidities between 0.2 and 0.8 and turbine with two, three and four blades is conducted. The numerical simulation models the flow field around a turbine rotor by solving the strong nonlinearity of URANS and SST k-ω turbulence model, utilizing the semi-empirical numerical model. To simulate the turbine in a variable pitch method, the user-defined function (UDF) code and the moving mesh method are used. The results show that variable pitch blades with high solidities are preferred when the initial self-starting torque is required. Moreover, the variable pitch blades are capable to produce more torque at high solidities. Therefore, the vortex interaction between upwind vortices and blades in downwind stream is decreased. The results verify that the power reduction of fixed pitch VAWT at high solidities could be solved by utilizing the variable pitch technique. Highlights • A straight-bladeVAWT with variable-pitch control system is investigated at different solidities. • The CFD method based k-w SST turbulence model is employed. • To simulate the turbine in a variable pitch method, the user-defined function (UDF) code is used. • The variable pitch blade produces fewer and smaller vortices, especially at high solidities. • At high solidities, the variable pitch have higher power production and is more controllable. [ABSTRACT FROM AUTHOR]

Abstract Orthopter-type Vertical Axis Wind Turbines (O-VAWT) are energy capturing devices which are suitable for micro-generation in urban areas. This paper aims to study the effect of number of blades (solidity), Aspect Ratio (AR), and wind speed on the performance of a small-scale O-VAWT using experimental and numerical techniques. Wind tunnel experiments were carried out to measure the torque of two-, three, and four-bladed turbine, each at a set of different wind speeds and blade aspect ratios. Increasing solidity was achieved by either decreasing the blade aspect ratio or increasing the number of blades, both resulting in a higher peak power coefficient (C p,max) of the VAWT. The startup characteristics of the O-VAWT were also examined at different aspect ratios, and showed its capability to start-up even at low wind speeds. In addition, numerical simulations were carried out using an unsteady three-dimensional Delayed Detached Eddy Simulation (DDES) with Spalart Allmaras model. Numerical results of power coefficient were validated by comparison against available experimental data. Moreover, velocity and vorticity contours for the two-, three-, and four-bladed turbines, and pressure contours at different span-wise locations were thoroughly analyzed to link the flow field aerodynamics to relevant changes in power coefficient for different rotor solidities. Highlights • The effect of solidity on the performance of an Orthopter-type vertical axis wind turbine is experimentally investigated. • A CFD approach is employed to analyze the 3D flow structures around turbines of different solidities. • The maximum power coefficient attained by the turbine increases with solidity. • Adding more blades results in attaining the maximum power coefficient at lower tip speed ratios. [ABSTRACT FROM AUTHOR]

From early infancy, humans reason about the external world in terms of identifiable, solid, cohesive objects persisting in space and time. This is one of the most fundamental human skills, which may be part of our innate conception of object properties. Although object permanence has been extensively studied across a variety of taxa, little is known about how non-human animals reason about other object properties. In this study, we therefore tested how domestic horses (Equus ferus caballus) intuitively reason about object properties like solidity and height, to locate hidden food. Horses were allowed to look for a food reward behind two opaque screens, only one of which had either the proper height or inclination to hide food rewards. Our results suggest that horses could not intuitively reason about physical object properties, but rather learned to select the screen with the proper height or inclination from the second set of 5 trials. [ABSTRACT FROM AUTHOR]

As the power efficiency is affected by every aspect of a wind turbine and its blades, a 2D-computational investigation of several key parameters is proposed after which actual experiments are performed. Six parameters are examined in the computational investigation: installation angle; blade airfoil; chord length; number of blades; radius of an impellor; and wind speed. To find out the optimum performance of a Vertical Axis Wind Turbine or VAWT, one appropriate parameter is selected at each section of the simulation progression. Afterwards, an experimental prototype of wind turbine is fabricated and put into an air-dynamic test to ascertain the validity of the previous CFD simulation. [ABSTRACT FROM AUTHOR]

This paper presents a study on the effect of solidity and airfoil profile on the performance of Vertical Axis Wind Turbines (VAWTs). A 1.1 kW commercially viable Darrieus VAWT was studied using ANSYS Fluent. Four different airfoils – NACA 0012, NACA 0015, NACA 0030 and AIR 001 – were considered in the analysis. The tip speed ratios (λ) were varied from 1 to 2.5 with an incoming wind velocity of 10 m/s. It was observed that NACA 0030 performed better at lower values of λ due to long duration of attached flow; while NACA 0012 performed better at λ > 1.8 with a wider range of λ. The shed vortex dissipates much faster for thinner airfoils than for thicker airfoils at higher values of λ. Two bladed VAWTs generated more power than the three bladed turbines. This indicated that turbines with lower solidity perform better at high λ. [ABSTRACT FROM AUTHOR]

Wind energy technology has seen steady growth in the energy market as a clean, renewable source of energy. This has brought attention to areas with moderate wind energy potentials. Darrieus type Vertical Axis Wind Turbines (VAWTs) allow capturing of this potential for energy production at a cost-effective scale. To improve the performance of these turbines their design needs to be optimized. With better manufacturing methods currently available cambered blades are being investigated to improve the performance of these turbines. In particular, turbine solidity is investigated in this paper due to different airfoil chord lengths and different number of blades. The analysis is conducted following high fidelity CFD modeling in unsteady, turbulent regimes in Arbitrary Lagrangian Eulerian formulation accounting for the sliding/rotating rotor's domain configuration that emphasizes the role of rotor blades interaction. The study showed that low solidity turbines with cambered blades operate at low coefficients of performance (C P ) over a large range of tip speed ratios (TSRs). High solidity turbines, with solidity close to unity, have much higher C P, but at smaller TSRs and a short range of TSRs. Medium solidity turbines, as well as turbines with solidity greater than unity, are faced with considerable interaction which compromises their operation at TSRs as low as one. The larger chord length helps improve the torque production of the turbine. The change in number of blades leads to a large dispersed wake behind the rotor which is unfavorable for deployment of an array of turbines. [ABSTRACT FROM AUTHOR]