Critical review of the trailing edge condition in steady and unsteady flow. Blade flutter in compressors and fans: Numerical simulation of the aerodynamic loading

Existing interpretations of the trailing edge condition, addressing both theoretical and experimental works in steady, as well as unsteady flows are critically reviewed. The work of Kutta and Joukowski on the trailing edge condition in steady flow is reviewed. It is shown that for most practical airfoils and blades (as in the case of most turbomachine blades), this condition is violated due to rounded trailing edges and high frequency effects, the flow dynamics in the trailing edge region being dominated by viscous forces; therefore, any meaningful modelling must include viscous effects. The question of to what extent the trailing edge condition affects acoustic radiation from the edge is raised; it is found that violation of the trailing edge condition leads to significant sound diffraction at the tailing edge, which is related to the problem of noise generation. Finally, various trailing edge conditions in unsteady flow are discussed, with emphasis on high reduced frequencies

On folding of fuzzy dynamical chaotic manifold

In this paper, we introduce some types of fuzzy dynamical chaotic manifold .We will also introduce a new type of folding, which is applied to fuzzy dynamical chaotic manifold and we will study the relation between the geometric folding and the chaotic folding of fuzzy dynamical chaotic manifold into itself. And the fuzzy dynamical chaotic manifold will be an achieved deduced

Experimental analysis of vacuum pressure and gas flow rate in structured-core transparent vacuum insulation panels

The notion that modern buildings should strive to be net-zero energy buildings (NZEBs) is widely accepted. One of the causes leading to high energy usage for space heating, resulting in avoidable carbon emissions, is heat loss via building windows. In order to improve window’s insulation in existing buildings, structured-core transparent vacuum insulation panels (TVIPs) are proposed. TVIPs mainly consist of the structured core material, the low-emissivity film, and the transparent gas barrier envelope. TVIPs have high insulation performance and are inexpensive to manufacture and can be easily installed. Therefore, TVIPs have the potential to improve window’s insulation in existing buildings at a low cost. However, it is necessary to overcome the issue of preventing the pressure rise inside TVIP after vacuum sealing. The authors constructed an experimental setup to quantify the effect of reduction of gas flow rate in TVIP after evacuation by applying the pressure-rate-of-rise-method. In this experiment, a gas barrier film with a straw was used as the vacuum chamber. This could reproduce the pressure increase in the TVIP after sealing and the gas flow rate in the TVIP is evaluated. The experimental result shows that the coated core material and the enclosing getter agent lowered the pressure rise and gas flow rate in TVIP by combining concurrent evacuation and heating. Furthermore, after extending the simultaneous vacuuming and heating period to 8 h and applying the coated core material, and enclosing the getter agent, the internal pressure in TVIP may be lowered to around 1 Pa after 30 min after halting vacuuming. It was confirmed that this pressure satisfied the performance required for TVIPs, and the result was much closer to the realization of TVIPs

Influence of a Hybrid MPPT Technique, SA-P&O, on PV System Performance under Partial Shading Conditions

The electricity sector has been undergoing profound transformations. In particular, the Portuguese self-consumer regime has allowed customers of the medium and low voltage electricity grid to be producers/consumers of electricity, actively contributing to greater energy efficiency. In this context, the energy that comes from the sun is not used to its maximum. In addition, photovoltaic cells have a characteristic operating curve (voltage vs. current), in which any operating point is reflected. Within this curve, there is a particular point known as the maximum power point (MPP) at which the cell supplies the maximum power output to a load. If the cell does not operate at this point, it has lower efficiency values. To harness maximum power under standard and dynamic shading conditions, there are various techniques of low complexity for capturing maximum power. We present a maximum power point tracking (MPPT) algorithm capable of dealing with the problem of partial shading. This algorithm involves modifying one of the most used algorithms within photovoltaic systems, known as P&O, using a simulated annealing (SA) algorithm. P&O is often used due to its straightforward implementation, but it is susceptible to partial shade conditions. Sampling was added to this algorithm to a better approach to the point of maximum power using the SA, and then to attain a more precise convergence with P&O. Implementing a maximum power point tracking method under partial shading was the major goal of this study

Assessing Spiritual Well-Being of Arab Muslim Prostate Cancer Survivors: A Reflection for a New Spiritual Health Care Policy

Religious and spiritual beliefs are some of numerous factors that influence quality of life outcome of cancer survivors. Spirituality is believed to be an important component of overall well-being and it is especially significant in relation to how cancer survivors cope with their morbidity. The purpose of this study was to explore spiritual well-being of Arab, Muslim prostate cancer survivors living in Gaza Strip, Palestine. A cross-sectional design was used in this study using the Spiritual Well-Being Scale (SWBS). A total of 117 Arab, Muslim patients diagnosed with prostate cancer from Gaza Strip participated in this study. Results revealed high scores of SWBS. Score for the total SWBS was 101.16 (±5.47) while was 58.91 (2.06±) for Religious Well-Being (RWB) subscale and 42.25 (±4.58) for Existential Well-Being (EWB) subscale. Scores were not affected by demographic characteristics of participants

On the History of the Paradigmatic Alternations of Labio-dental Fricatives in English

This article discusses and explains the sources of the alternations between the /f/ and /v/ sounds in English. It shows that the three main mechanisms of diachronic phonology responsible for such paradigmatic alternations are sound change, analogical change, and borrowing. Moreover, it explains the interplay between sound change and analogical change

Thermal performance analysis of a new structured-core translucent vacuuminsulation panel in comparison to vacuum glazing: Experimental and theoretically validated analyses

The notion at which, nowadays, building sector is being recognized to be nearly zero-energy buildings (NZEBs) relies partly on the thermal performance of its fabric insulation. Vacuum glazing (VG) technology attracted the research interest as an option to reduce heat loss through windows. However, the total glazing thermal transmittance (U-value) for VG increases with the use of smaller glazing area due to the edge-seal effects, due to the thermal short-circuit around the edges and the overall construction cost of VG leading to an unaffordable option to deal with energy conservation of buildings. Therefore, this study aims to propose a new structured core transparent vacuum insulation panel (TVIP) to accomplish insulation for the windows without edge sealing effect, with lower cost and can be easily retrofitted to the conventional windows of the existing buildings. To do this, VG and TVIP were constructed and their thermal conductivity were measured using heat flow meter apparatus. In addition, a 3D finite volume model considering the effect of surface to surface radiation, gas conduction, and thermal bridges through the spacer material and sealing material is developed. The model is validated with the experiments in this work and with the data for VG in the literature. The effect of vacuum pressure increase is simulated to mimic the vacuum deterioration problem and the effect of glazing size on the insulation performance of both VG and TVIP were investigated. The results indicate that for a smaller glazing area of less than 30 cm × 30 cm, the TVIP accomplished lower U-value compared with the VG at vacuum pressure of 0.1 Pa and 1 Pa. While, at a vacuum pressure of 10 Pa, the TVIP attained a lower U-value over the entire range of the investigated glazing sizes. Further, the edge-seal effect in the VG is diminished with the use of TVIP. Furthermore, the material cost per unit area of the TVIP is three times less than the cost of VG at laboratory scale. The results of the current study can guide vacuum window designers and researchers to further enhance the performance of TVIP based window to compete for the VG in the markets

Patterns of Reinterpretation of Word Formation of Arabized Words

This article discusses morphological adaptation showing that the degree of assimilation depends on several factors. It shows that certain morphological elements or categories are more susceptible to adaptation than others. For example, concrete lexical items, especially nouns, are more easily integrated than abstracts and grammatical elements. One of the most important processes which can be used to incorporate newly introduced items is the simple derivation (small derivation); the stem is modified by different kinds of affixation. In this process, the morphology of the borrowed word is modeled according to the well-known Arabic "?awzan" through what might be termed a proportional analogical method of derivation or back formation. Two main groups of borrowed words are recognized: The first group includes words which can assimilate completely and become productive for other derivations. Words in this class can be analysed into two discontinuous morphemes (consonantal roots and vocalic patterns). The other group includes borrowed words which cannot be integrated completely because of their incompatibility with the structure of· the Arabic language. Such words cannot be considered as composed of two discontinuous morphemes; instead, the one continuous morpheme approach is adopted. Finally, a suggestion is made to generalize the one continuous morpheme analysis because it is more practical, less abstract, and more capable of avoiding the many exceptions and unresolved problems in dealing with borrowed words