INTRODUCTION OF INTERCOOLING IN A HIGH BYPASS JET ENGINE

ABSTRACT In this paper an exercise to introduce intercooling in a high bypass civil turbofan is outlined. The engine selected as the basic propulsion system is a three spool high bypass turbofan with a bypass ratio 6.4. The air leaving the IP compressor is cooled in the bypass duct prior to entering the HP compressor. This preliminary investigation appears to indicate that the main benefit to be gained is an increase in the net thrust from the engine without increasing the turbine inlet temperature. To keep engine diameter constant, the bypass ratio has not been changed. This results in a requirement to significantly increase the pressure ratio to reduce the SFC levels to an acceptable value. A sizing exercise has been carried out to understand the weight and volume penalties imposed by heat pipe intercooling hardware. The preliminary sizing exercise indicates that the weight penalty is very large. The performance of the aircraft using the intercooled engines is also investigated and some improvements in performance are predicted. Overall this investigation is considered to be positive so that further investigations should be considered. It appears that an intercooled engine can produce a somewhat higher thrust at a given turbine entry temperature at similar SFC levels of current engines, or, if a small increase in SFC is acceptable, the increase in thrust is quite important. NOMENCLATUR

STOICHEIOMETRY WITHIN THE FRAMEWORK OF GREEK SECONDARY EDUCATION CHEMISTRY CURRICULUM

A study is carried out by means of distributing a duo of questionnaires to secondary education students in a variety of schools in Northern Greece. The first of these questionnaires is aiming at the identification of the initial degree of general chemical concepts and ideas assimilation by the students and is distributed by their teachers during an early teaching hour in the senior high-school grade B class. The second questionnaire is distributed during the final weeks of the school year and aims at the mapping of integration of concepts related to stoicheiometry to students’ chemical background, since grade B of senior high-school is loaded with introductory organic chemistry and the corresponding wide variety of reactions on which a vast amount of problems to be solved is based. The validity of the questionnaires and their efficiency in fulfilling the scope of the current research is carried out by means of the application of certain post-statistical indices with the final goal being their utilization as a diagnostic tool for probing student understanding of chemical concepts

USING ASPECT-ORIENTED SOFTWARE DEVELOPMENT IN REAL-TIME EMBEDDED SYSTEMS SOFTWARE A Review of Scheduling, Resource Allocation and Synchronization

Abstract: Timeliness and criticality of a process are the two main concerns when designing real-time systems. In addition to that embedded systems are bounded by limited resources. To achieve these concerns while at the same time using a minimal amount or resources, real-time embedded systems use different techniques such as task scheduling, resource management and task synchronization. These techniques involve a number of the modules of the system which makes the use of Aspect-Oriented Software Development imperative. AOSD is a programming technique which uses the notion of join points to capture specific locations in code execution and then use advices to insert new code. This paper examines existing work in the development of schedulers, resource allocation agents and synchronization techniques using Aspect-Oriented Software Development in real-time embedded systems. An analysis of the existing research is used to describe the advantages of using AOSD over conventional OOP methods and to identify areas where further research may be required.

Molecular and Biologic Effects of Platelet-Rich Plasma (PRP) in Ligament and Tendon Healing and Regeneration: A Systematic Review

Platelet-rich plasma (PRP) has been introduced and applied to a wide spectrum of acute and chronic ligament and tendon pathologic conditions. Although the biological effect of PRP has been studied thoroughly in both animal and human studies, there is no consensus so far on the exact mechanism of its action as well as the optimal timing and dosage of its application. Therefore, we conducted a systematic review aiming to evaluate the molecular effect of the administration of PRP in tendoligamentous injuries and degenerative diseases. The literature search revealed 36 in vitro and in vivo studies examining the healing and remodeling response of animal and human ligament or tendon tissues to PRP. Platelet-rich plasma added in the culture media was highly associated with increased cell proliferation, migration, viability and total collagen production of both ligament- and tendon-derived cells in in vitro studies, which was further confirmed by the upregulation of collagen gene expression. In vivo studies correlated the PRP with higher fibroblastic anabolic activity, including increased cellularity, collagen production and vascularity of ligament tissue. Similarly, greater metabolic response of tenocytes along with the acceleration of the healing process in the setting of a tendon tear were noticed after PRP application, particularly between the third and fourth week after treatment. However, some studies demonstrated that PRP had no or even negative effect on tendon and ligament regeneration. This controversy is mainly related to the variable processes and methodologies of preparation of PRP, necessitating standardized protocols for both investigation and ap-plication

A Review of Aspect-Oriented Software Development Techniques Used in Real-Time and Embedded Systems Software

Abstract. Timeliness and criticality of a process are the two main concerns when designing real-time systems. In addition to that embedded systems are bounded by limited resources. To achieve timeliness and conform to the criticality issues of various processes while at the same time using a minimal amount or resources, real-time embedded systems use different techniques such as task scheduling, resource management and task synchronization. All of these techniques involve a number of the modules of the system which makes the use of Aspect-Oriented Software Development imperative. AOSD is a programming technique which uses the notion of join points to capture specific locations in code execution and then use advices to insert new code. This paper examines existing work in the development of schedulers, resource allocation agents and synchronization techniques using Aspect-Oriented Software Development in real-time systems and more specifically in embedded systems. An analysis of the existing research is used to describe the advantages of using AOSD over conventional OOP methods and to identify areas where further research may be required.

A New Symbolic Time Series Analysis Method Based on Time-to-Space Mapping, through a Symmetric Magnetic Field, Quantized by Prime Numbers

This work presents a new analysis method for two-symbol symbolic time series based on the time-to-space mapping achieved through a device of current carrying circular rings. An algorithm based on the theory of prime numbers is proposed for the approximate estimation of the stratified magnetic field produced by the aforementioned device. The main property of the specific algorithm is that it quantizes the stratified magnetic field. If a two-symbol symbolic time series is used to determine the flow directions of the rings’ currents, a time-to-space mapping of the dynamics of the system producing the time series is observed. A unique “fingerprint” of the symbolic dynamics is shaped by the spatial allocation of the values of the six-valued symmetric quantized magnetic field produced by the device. This allows for the quantitative evaluation of the original system’s dynamics by analyzing the resultant quantized magnetic field values space allocation, in a spectrum ranging from the lack of dynamics (randomness) to the presence of dynamics at all scales (criticality). Two examples of application–corresponding to the extremes of the dynamics spectrum, specifically, for symbolic time series resulting from (a) a random numbers generator and (b) the spin alternation of 2D-Ising in its critical state, verify the reliable time-to-space mapping of the involved symbolic dynamics. Moreover, an application to the symbolic sequence produced by the DNA of the GAPDH (Glyceraldehyde-3-Phosphate Dehydrogenase) human gene is presented as a real-world, intermediate dynamics case. The proposed symbolic time series analysis method presents the advantage that can take into account information related to both symbols, which is particularly useful in analyzing two-symbol time series of relatively short length where the probabilities of occurrence of the two symbols are not equal. By inferring the universality class of an artificial-neural-network-based hybrid spin model through the value of the critical exponent δ, it is shown that for such time series, the proposed method provides a unique way to expose the real dynamics of the underlying complex system, in contrast to the analysis of waiting times in the time domain that leads to an ambiguous quantitative result

Decentralized Blockchain-Based IoT Data Marketplaces

In present times, the largest amount of data is being controlled in a centralized manner. However, as the data are in essence the fuel of any application and service, there is a need to make the data more findable and accessible. Another problem with the data being centralized is the limited storage as well as the uncertainty of their authenticity. In the Internet of Things (IoT) sector specifically, data are the key to develop the most powerful and reliable applications. For these reasons, there is a rise on works that present decentralized marketplaces for IoT data with many of them exploiting blockchain technology to offer security advantages. The main contribution of this work is to review the existing works on decentralized IoT data marketplaces and discuss important design aspects and options so as to guide (a) the prospective user to select the IoT data marketplace that matches their needs and (b) the potential designer of a new marketplace to make insightful decisions