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Artykuły w czasopismach na temat "PERMISSIONS COMPARISON"
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AlJarrah, Mohammed N., Qussai M. Yaseen i Ahmad M. Mustafa. "A Context-Aware Android Malware Detection Approach Using Machine Learning". Information 13, nr 12 (30.11.2022): 563. http://dx.doi.org/10.3390/info13120563.
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The Android platform has become the most popular smartphone operating system, which makes it a target for malicious mobile apps. This paper proposes a machine learning-based approach for Android malware detection based on application features. Unlike many prior research that focused exclusively on API Calls and permissions features to improve detection efficiency and accuracy, this paper incorporates applications’ contextual features with API Calls and permissions features. Moreover, the proposed approach extracted a new dataset of static API Calls and permission features using a large dataset of malicious and benign Android APK samples. Furthermore, the proposed approach used the Information Gain algorithm to reduce the API and permission feature space from 527 to the most relevant 50 features only. Several combinations of API Calls, permissions, and contextual features were used. These combinations were fed into different machine-learning algorithms to show the significance of using the selected contextual features in detecting Android malware. The experiments show that the proposed model achieved a very high accuracy of about 99.4% when using contextual features in comparison to 97.2% without using contextual features. Moreover, the paper shows that the proposed approach outperformed the state-of-the-art models considered in this work.
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Aftab, Muhammad Umar, Zhiguang Qin, Negalign Wake Hundera, Oluwasanmi Ariyo, Zakria, Ngo Tung Son i Tran Van Dinh. "Permission-Based Separation of Duty in Dynamic Role-Based Access Control Model". Symmetry 11, nr 5 (15.05.2019): 669. http://dx.doi.org/10.3390/sym11050669.
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A major development in the field of access control is the dominant role-based access control (RBAC) scheme. The fascination of RBAC lies in its enhanced security along with the concept of roles. In addition, attribute-based access control (ABAC) is added to the access control models, which is famous for its dynamic behavior. Separation of duty (SOD) is used for enforcing least privilege concept in RBAC and ABAC. Moreover, SOD is a powerful tool that is used to protect an organization from internal security attacks and threats. Different problems have been found in the implementation of SOD at the role level. This paper discusses that the implementation of SOD on the level of roles is not a good option. Therefore, this paper proposes a hybrid access control model to implement SOD on the basis of permissions. The first part of the proposed model is based on the addition of attributes with dynamic characteristics in the RBAC model, whereas the second part of the model implements the permission-based SOD in dynamic RBAC model. Moreover, in comparison with previous models, performance and feature analysis are performed to show the strength of dynamic RBAC model. This model improves the performance of the RBAC model in terms of time, dynamicity, and automatic permissions and roles assignment. At the same time, this model also reduces the administrator’s load and provides a flexible, dynamic, and secure access control model.
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Kumar, Naveen, i Dr Gopal Singh. "The Performance Analysis of Optimized Integrated Framework for Smart Grid". Indian Journal of Signal Processing 2, nr 3 (30.08.2022): 1–4. http://dx.doi.org/10.54105/ijsp.d1010.082322.
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Supervisory Control and Data Acquisition system are monitoring and controlling system. It focuses on the supervisory level, not the full control permissions. It is gathering real-time data with the help of several kinds of sensors. Internet of Things (IoT) is a three-dimension any time, any place anything connectivity for anything. This paper performing the comparison between the SCADA and optimization framework for smart grid. A power quality model is integrated with the optimization framework. Moreover, this paper focused on the comparison of optimized framework with SCADA.
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Zhao, Bin, Guiyue Zheng, Yilong Gao i Yanchen Zhao. "Access-Control Model of Super Business System Based on Business Entity". Electronics 11, nr 19 (27.09.2022): 3073. http://dx.doi.org/10.3390/electronics11193073.
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To address the problem that the traditional access-control model is no longer suitable for access control and authorization in the super business system—which has the characteristics of many businesses and complex permissions—a business entity-based access-control model (BE-BAC) is proposed in this paper. The BE-BAC model realizes the relationship between users, business entities, and business permissions. Firstly, according to the characteristics of the super business system, the concept of business entity is put forward, introducing the composition and relationship of the business entity. Secondly, the business entity is introduced into the access-control model, formally describing the basic relationship, constraint, mapping, and authorization strategy of the BE-BAC model. Finally, the access-control workflow, based on the business entity, is designed, and the security analysis and comprehensive comparison of the model are carried out. Compared with the existing access-control model, the BE-BAC model has higher security and flexibility, and better protects resources, through more secure access-request decisions.
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Zhang, Shijia, Yilin Liu i Mahanth Gowda. "I Spy You". Proceedings of the ACM on Interactive, Mobile, Wearable and Ubiquitous Technologies 6, nr 4 (21.12.2022): 1–31. http://dx.doi.org/10.1145/3569486.
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This paper presents iSpyU, a system that shows the feasibility of recognition of natural speech content played on a phone during conference calls (Skype, Zoom, etc) using a fusion of motion sensors such as accelerometer and gyroscope. While microphones require permissions from the user to be accessible by an app developer, the motion sensors are zero-permission sensors, thus accessible by a developer without alerting the user. This allows a malicious app to potentially eavesdrop on sensitive speech content played by the user's phone. In designing the attack, iSpyU tackles a number of technical challenges including: (i) Low sampling rate of motion sensors (500 Hz in comparison to 44 kHz for a microphone). (ii) Lack of availability of large-scale training datasets to train models for Automatic Speech Recognition (ASR) with motion sensors. iSpyU systematically addresses these challenges by a combination of techniques in synthetic training data generation, ASR modeling, and domain adaptation. Extensive measurement studies on modern smartphones show a word level accuracy of 53.3 - 59.9% over a dictionary of 2000-10000 words, and a character level accuracy of 70.0 - 74.8%. We believe such levels of accuracy poses a significant threat when viewed from a privacy perspective.
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Baker, Paul, i Rachelle Vessey. "A corpus-driven comparison of English and French Islamist extremist texts". International Journal of Corpus Linguistics 23, nr 3 (29.10.2018): 255–78. http://dx.doi.org/10.1075/ijcl.17108.bak.
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Abstract Using corpus linguistics and qualitative, manual discourse analysis, this paper compares English and French extremist texts to determine how messages in different languages draw upon similar and distinct discursive themes and linguistic strategies. Findings show that both corpora focus on religion and rewards (i.e. for faith) and strongly rely on othering strategies. However, the English texts are concerned with world events whereas the French texts focus on issues specific to France. Also, while the English texts use Arabic code-switching as a form of legitimation, the French texts use a formal register and quotation from scripture in discussions of permissions, rights, obligations and laws. Finally, the English texts refer to and justify violence to a greater extent than the French texts. This paper contributes to the field of terrorism studies and the field of corpus linguistics by presenting a new approach to corpus-driven studies of discourse across more than one language.
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Karali, Mehmet Akif, i Özkan Ginesar. "Investigation of Social Studies Teacher Candidates’ Attitudes Towards Renewable Energy Sources". Open Journal for Educational Research 7, nr 1 (30.05.2023): 13–22. http://dx.doi.org/10.32591/coas.ojer.0701.02013k.
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This research was prepared in order to examine the attitudes of social studies teacher candidates towards renewable energy sources in terms of various variables. Convenient sampling, one of the purposeful sampling methods, was preferred in the research and the sample group of the research consists of 250 teacher candidates, who are the last level students of universities who teach social studies. In the research, the data were collected by taking the necessary permissions and transferring the scale used to the online environment, taking into account the cost and economic conditions. The Attitude Scale Towards Renewable Energy Sources developed by T. Güneş, K. Alat, and A. İ. C. Gözüm, was used after obtaining the necessary permissions. In addition, the demographic information form prepared by taking the necessary expert opinion within the scope of this research was used as a data collection tool in the research. The Attitude Scale Towards Renewable Energy Sources used in the research was prepared in a 5-point Likert type consisting of 26 items. The causal comparison design, which is among the quantitative methods, was preferred in the research. The data obtained in the study were analyzed using independent groups t-test and one-way analysis of variance (ANOVA).
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Chen, Yanji, Mieczyslaw M. Kokar, Jakub Moskal i Kaushik R. Chowdhury. "Metrics-Based Comparison of OWL and XML for Representing and Querying Cognitive Radio Capabilities". Applied Sciences 12, nr 23 (23.11.2022): 11946. http://dx.doi.org/10.3390/app122311946.
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Collaborative spectrum access requires wireless devices to perform spectrum-related tasks (such as sensing) on request from other nodes. Thus, while joining the network, they need to inform neighboring devices and/or the central coordinator of their capabilities. During the operational phase, nodes may request other permissions from the the controller, like the opportunity to transmit according to the current policies and spectrum availability. To achieve such coordinated behavior, all associated devices within the network need a language for describing radio capabilities, requests, scenarios, policies, and spectrum availability. In this paper, we present a thorough comparison of the use of two candidate languages—Web Ontology Language (OWL) and eXtensible Markup Language (XML)—for such purposes. Towards this goal, we propose an evaluation method for automating quantitative comparisons with metrics such as precision, recall, device registration, and the query response time. The requests are expressed in both SPARQL Protocol and RDF Query Language (SPARQL) and XML Query Language (XQuery), whereas the device capabilities are expressed in both OWL and XML. The evaluation results demonstrate the advantages of using OWL semantics to improve the quality of matching results over XML. We also discuss how the evaluation method can be applicable to other scenarios where knowledge, datasets, and queries require richer expressiveness and semantics.
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Coşkun, Kerem, i Cihan Kara. "What Happens During Teacher–Student Interaction in the First Year of Primary School? A New Explanation". SAGE Open 10, nr 2 (kwiecień 2020): 215824402092656. http://dx.doi.org/10.1177/2158244020926566.
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The present research aims to develop a theory on teacher–student interaction in the first year of primary school period. The present research was designed in grounded theory research which is one of the qualitative research traditions. A total of 18 primary school children started the first year of primary school. Data were collected through participant observation. Participant observation was launched after all necessary ethical permissions were taken from local education authority, the participant children, their teacher, and parents. Data were analyzed through constant comparison within three stages as open coding, axial coding, and selective coding. It was reported that the teacher and the first graders mutually developed strategies and there were several circumstances in the interaction that nested behavioral problems.
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Ekaputri, Januarti Jaya, i M. Shahib Al Bari. "The comparison of regulations on fly ash as a hazardous waste in Indonesia and several countries". MEDIA KOMUNIKASI TEKNIK SIPIL 26, nr 2 (2.02.2021): 150–62. http://dx.doi.org/10.14710/mkts.v26i2.30762.
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This paper aims to encourage the Indonesian government to review the 2014 Government Regulation (PP) number 101 related to coal-ash. Fly ashes at power plants overload the landfills and requires complete handling solution. The utilization of fly ash in Indonesia are facing the issues, one of these is the categorization of fly ash as a hazardous waste. As a result, its utilization requires permissions from the ministry of environment and forestry. In this paper, a comparative study of fly ash classification as hazardous waste in India, United States of America, China and Vietnam was conducted. India and China are the coal importer from Indonesia. US regulation was once referred when drafting PP number 101. Vietnam is chosen as comparison in Southeast Asia. The Toxicity Characteristic Leaching Procedure (TCLP) results of fly ashes from 16 Indonesian power plants proved that their toxic content was lower than the TCLP parameters in the regulation. Acute Oral Toxicity Test (LD50) results showed that fly ash and bottom ash with dosage up to 7000 mg/kg did not cause fatalities. This study is a reference for the Indonesian government to verify the status of fly ash to be utilized as much as possible in various fields.
Rozprawy doktorskie na temat "PERMISSIONS COMPARISON"
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KUMAR, NIRAJ. "ANDROID APP REPACKAGING DETECTION USING SIGNING CERTIFICATE AND PERMISSIONS COMPARISON". Thesis, 2018. http://dspace.dtu.ac.in:8080/jspui/handle/repository/19109.
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Android eco system works in two steps as far as an application developer is concerned. In the first
step, developers design and develop an Android app and subsequently publish it on Google Play
Store either as paid apps or with some advertisements to earn monetary benefit or sometimes as
free app just for building user base. Besides the bona fide Android ecosystem, there is a parallel
dark world of malicious attackers who repackage other developer's application (Free apps available
in Play Store or other app stores) and publish it with their own name. Alternatively, they add
advertisements with their own bank accounts or even add malicious code and use it for their own
benefit.
In a similar fashion, malicious attackers embed malware payload into the original applications so
as to gain control of the mobile devices on which they are running to retrieve the private data of
the user, stealthily read or send SMS messages to premium rate numbers, read banking credentials
and so on. Although there are many identification methods which have been used traditionally to
detect these repackaged applications existing in various Android app stores. However, it is not
always effective to analyse any new application.
Repackaged apps are a serious vulnerability these days in Android phones. Various threat
mitigation measures have been devised like watermarking in case of rooted device. But, a defence
mechanism that prohibits repackaged apps from running on a user device (non-rooted device) is
not common. Our repackage-proofing technique for Android apps is trustworthy and covert.
Repackaged apps present considerable challenge to the security and privacy of smartphone users.
But fortunately such apps can be made to crash (randomly crash to confuse attackers) using
keystore check as well as permissions added in repackaged code. Even other techniques like code
obfuscation using ProGuard tool are helpful. It does not require any change at the Framework or
System level. Private key used to sign the apk is with the original developer.
Any app which is installed in an Android system need to pass signature validation.
PackageManager API reads an apk and extracts the app information. It then saves the information
in three different files on device path /data/system. Out of these three files, the most important is
packages.xml. It contains key information like names, code paths, public keys, permissions, etc.,
2 | P a g e
for all the installed apps. PackageManager API is used to retrieve Kr from the file. We split this
Kr value into 8 equal parts and store it as constants in different classes. At runtime, we merge these
parts to recreate Kr and compare it with Kr value returned by making use of PackageManager. For
repackaged apps as signing key has changed, the two Kr values will be different.
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Liao, Fang-yu, i 廖方瑜. "Comparison between Permission-based Email and Spam: The Impact of Advertising Value, Perceived Intrusiveness, and Advertising Attitude on Advertising Effectiveness". Thesis, 2007. http://ndltd.ncl.edu.tw/handle/79181742658325970547.
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碩士國立成功大學
企業管理學系碩博士班
95
From the viewpoint of marketing communication, new digital marketing channels, such as those concerned with the Internet and email, are considered to be powerful opportunities to reach consumers by delivering a personalised message with relevant content. With low marginal cost, email presents itself as an effective way to engage customers in dialogue: messages can be tailored to each customer according to his/her stage of the buying process. Email also allows customers to select their own preferences. Permission marketing applied in emails helps marketers to deliver relevant messages to consumers that are different from spam. However, consumer perception suggests that permission for such email is often assumed by an ambiguous evaluation. The perceived advertising value and perceived intrusiveness of such emails (including spam and permission emails) can be assessed by consumers indicating their opinions based on the content and presence of emails by receipting the messages. The goal of Internet advertising is to build brand names and induce consumer response to commercial campaigns and an assessment of consumer attitude towards the senders of such emails has been introduced as a measure of the effectiveness of advertising. Between the relation of perceived intrusiveness and advertising effectiveness, advertising attitude has been adopted as a mediator, as prior research has found it to be a predictor of advertising effectiveness. Besides an investigation into the causal relations between each construct, a comparison between permission email and spam has been conducted in this research. The results supported the hypotheses and demonstrated a difference between spam and permission emails. The results gave evidence to support the theoretical statement and hence, offer keys to implementation to both the theory and management.
Książki na temat "PERMISSIONS COMPARISON"
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Karagodin, Valeriy, Ol'ga Nadonenko, Aleksandra Nikolaenkova, Svetlana Sokolova, Irina Smirnova, Kseniya Baranova, Andrey Kokovin i in. Appointment of forensic examinations. ru: INFRA-M Academic Publishing LLC., 2022. http://dx.doi.org/10.12737/1853497.
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The textbook provides information about the structure of the forensic expert system of the Russian Federation, discusses procedural and organizational issues of preparation, appointment and production of forensic examinations, features of the design of a procedural document - a resolution on the appointment of a forensic examination, including in connection with differences between categories of forensic experts. The stages of the emergence and development of certain types of forensic examinations are shown. The basic recommendations of forensic experts on the preparation of materials, comparison samples for the appointment of specific forensic examinations are systematically stated and justified, in accordance with various investigative situations, formulations of questions submitted for expert permission are proposed, recommendations on the seizure, packaging, storage and transportation of objects for specific types of forensic examinations are given. The recommendations are illustrated with examples from the authors' expert practice.
The work was prepared by an author's team of acting forensic experts with practical experience from 8 to 30 years.
Meets the requirements of the federal state educational standards of higher education of the latest generation.
For students, trainees, postgraduates, adjuncts and teachers of law schools and faculties, practitioners of investigative and investigative law enforcement agencies, judges, prosecutors, lawyers, as well as for a wide audience of persons interested in criminology and forensic examination.
Części książek na temat "PERMISSIONS COMPARISON"
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"Propagated Fish in Resource Management". W Propagated Fish in Resource Management, redaktorzy DANIEL B. FENNER, MAUREEN G. WALSH i DANA L. WINKELMAN. American Fisheries Society, 2004. http://dx.doi.org/10.47886/9781888569698.ch39.
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<em>Abstract.</em>—Private angling groups in Oklahoma have requested permission to stock rainbow trout <em>Oncorhynchus mykiss </em>into streams of northeastern Oklahoma although little is known regarding interactions between introduced rainbow trout and native fishes in these systems. Our study objectives were to assess diet overlap between introduced rainbow trout and native smallmouth bass <em>Micropterus dolomieu</em>, shadow bass <em>Ambloplites ariommus</em>, and bluegill sunfish <em>Lepomis macrochirus </em>in Brush Creek, Oklahoma, a small spring-fed Ozark stream. Rainbow trout diet composition differed from that of all three native fishes in the 2 months of comparison (March and May 2001), and rainbow trout diets contained relatively low numbers of prey. It is unlikely that exploitative competition for food resources occurred between rainbow trout and these three native fishes.
Streszczenia konferencji na temat "PERMISSIONS COMPARISON"
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Sahin, Durmus Ozkan, Oguz Emre Kural, Sedat Akleylek i Erdal Kilic. "Comparison of Regression Methods in Permission Based Android Malware Detection". W 2020 28th Signal Processing and Communications Applications Conference (SIU). IEEE, 2020. http://dx.doi.org/10.1109/siu49456.2020.9302502.
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Thomaz, Guilherme A., Gustavo F. Camilo, Lucas Airam C. de Souza i Otto Carlos M. B. Duarte. "Architecture and Performance Comparison of Permissioned Blockchains Platforms for Smart Contracts". W GLOBECOM 2021 - 2021 IEEE Global Communications Conference. IEEE, 2021. http://dx.doi.org/10.1109/globecom46510.2021.9685508.
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Xu, Tong, Binan Shou, Hankui Wang i Chao Sun. "The Application of Elevated Temperature Materials for USC Boilers in China". W ASME 2014 Symposium on Elevated Temperature Application of Materials for Fossil, Nuclear, and Petrochemical Industries. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/etam2014-1038.
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In this paper, the history of elevated temperature material production in China was reviewed, and the application status of elevated temperature materials for USC boilers in China was introduced. A comparison of Chinese standard GB5310 and ASME relevant codes of elevated temperature material designations was also proposed. Finally, statistical analysis of chemical compositions and mechanical properties of some domestic and imported material productions, including T/P91 and T/P92, was presented. Paper published with permission.
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Wiegand, Bernhard W. H. "A New Concept of Evaporation Plants: Thermal Vapor Recompression for Reducing Costs and Improving Product Quality". W ASME 1992 Citrus Engineering Conference. American Society of Mechanical Engineers, 1992. http://dx.doi.org/10.1115/cec1992-3804.
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GEA Wiegand has introduced a new evaporating concept tor concentrating orange juices by applying thermal vapor recompression (TVR). This technology is not new and has been used very successfully tor many decades in other industries but was never applied so far for citrus juice concentration. In this article a conventional 7-effect directly heated evaporating plant is set against a new 5-effect plant with thermal vapor recompression for comparison and to prove the many advantages of this concept with regard to low running and capital costs as well as product quality of the concentrate. Paper published with permission.
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Di Lillo, Patrizio, Luca Gaetani, Lorenzo Germoni i Alessandro Masia. "A Comparative Creep and Creep Fatigue Analysis of an Austenitic Steam Superheater". W ASME 2014 Symposium on Elevated Temperature Application of Materials for Fossil, Nuclear, and Petrochemical Industries. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/etam2014-1020.
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A steam superheater is a component which operates at elevated temperature in the creep regime. The component is normally not working in cycling conditions. Due to operation failures, the component has been subjected to several unplanned start-ups and shutdown. The SSH has reported a very high level of damage of the tubesheet to shell junction in field (high deformation and weld cracks). Several investigations have been performed to analyze the effect of temperature, pressure and external loads on the equipment with finite element techniques and different creep and creep-fatigue evaluation approaches: ASME III subsection NH, simplified inelastic analysis and a full creep model have been used. A comparison of the results is reported in this paper. Paper published with permission.
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Menon, Balji C. "Experience in the Verification of Energy Efficiency Design Index". W ASME/USCG 2013 3rd Workshop on Marine Technology and Standards. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/mts2013-0319.
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The Energy Efficiency Design Index (EEDI) that is part of a new Chapter 4 of MARPOL Annex 6 on Energy Efficiency Regulations is mandatory for new ships effective 1 January 2013. During the period from 2011 to the end of 2012, many of the major shipyards and shipping companies have voluntarily complied with the requirements of EEDI calculation and verification for their newbuilds. This paper outlines requirements of EEDI verification procedure and aspects of the verification method that are important to the calculation of EEDI reference speed from speed trials. This paper shows the outcome of the verification process that some new ships have gone through, the degree of compliance achieved and the experience gained in EEDI verification for three types of ships: tankers, bulk carriers and containerships. Sources of uncertainties associated with lack of complete information from sea trials are identified. Comparison of the attained and required EEDI for the three vessel types demonstrating the degree of compliance in Phases 0 and 1 are included. Paper published with permission.
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Anderson, David, Nadarajah Chithranjan, Maan Jawad i Antoine Martin. "Comparison of the Requirements of the British R5, French RCC-MRx, Proposed New Rules in ASME Section VIII, and API 579 Codes in the Design of a Cylinder Subjected to Pressure With Thermal Gradient at Elevated Creep Temperatures". W ASME 2014 Symposium on Elevated Temperature Application of Materials for Fossil, Nuclear, and Petrochemical Industries. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/etam2014-1041.
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The authors analyze two sample problems using four different international codes in the evaluation. The first is the British R5 code, the second is the French RCC-MRx code, third is the ASME Section VIII, Division 2, code using proposed new simplified rules taken from the ASME nuclear code section NH, and the fourth is the API 579 code. The requirements, assumptions, and limitations of each of the four codes as they pertain to the sample problems are presented. The first sample problem is for creep-fatigue analysis of a cylindrical shell subjected to internal pressure with a linear thermal gradient through the wall. The second sample problem is evaluating the critical buckling strength of the cylindrical shell under external pressure in accordance with proposed new rules in ASME Section VIII, Division 2, API 579, and a finite element analysis. Paper published with permission.
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Dewees, Dave, i Rahul Jain. "Evaluation of Limit Load Analysis Methods Applied to High Temperature Design: Part 1 — Consistent Material Modeling". W ASME 2014 Symposium on Elevated Temperature Application of Materials for Fossil, Nuclear, and Petrochemical Industries. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/etam2014-1039.
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Design-by-Rule codes (i.e. ASME Section I, EN 12952) already exist for elevated temperature (creep) design and have been successfully used for decades; however, there is motivation to optimize designs, or to assess non-standard ones. Limit Load Analysis (LLA) is the simplest advanced analysis method, and a powerful and widely-used tool for establishing compliance with required pressure part safety margins for operation at temperatures below the creep range. However, there is no direct relationship between LLA and elevated temperature allowable stresses and failure modes, such that the basic LLA methods or results must be manipulated in some way to be generally meaningful. With this in mind, review of proposed elevated temperature LLA methods (which are discussed in Part 2 of this work) by comparison to detailed transient inelastic finite element analysis allows for rigorous assessment of simplifications. Specification of an elevated temperature material model that is consistent with traditional allowable stresses for the detailed analysis is described in this paper (Part 1), and the material model and simplified methods are applied to the case of a typical steam header in the next (Part 2). Paper published with permission.
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Cao, Yiding, i Jian Ling. "Performance Simulations of a Gas Turbine Disk-Blade Assembly Employing Miniature Rotating Heat Pipes". W ASME 2009 Second International Conference on Micro/Nanoscale Heat and Mass Transfer. ASMEDC, 2009. http://dx.doi.org/10.1115/mnhmt2009-18141.
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With a substantially increased gas inlet temperature in modern gas turbine engines, the cooling of turbine disks is becoming a challenging task. In order to reduce the temperature at the disk rim, a new turbine disk incorporating radially rotating heat pipes has been proposed. The objective of this paper is to conduct a numerical investigation for the cooling effectiveness of the rotating heat pipe. One of the major tasks of this paper is to compare the performance between a proposed disk-blade assembly incorporating radially heat pipes and a conventional disk-blade assembly without the heat pipes under the same heating and cooling conditions. The numerical investigation illustrates that the turbine disk cooling technique incorporating radially rotating heat pipes is feasible. The maximum temperature at the rim of the proposed disk can be reduced by more than 100°C in comparison with that of a conventional disk without heat pipes. However, the average temperature at the blade airfoil surface can be reduced by only about 10 degrees. Therefore, the results indicate that the average temperature of the airfoil surface is not very sensitive to the disk cooling condition. In addition, both the heat pipe length and diameter have an important effect on the turbine disk cooling. Under the permission of material strength, a longer heat pipe or a larger heat pipe will produce a lower temperature at the proposed disk rim.
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Rhyner, Daniel J. "Evaluation of Horizontal Recirculatory Air Curtain Efficiencies: Cooler to Conditioned Space". W ASME 2014 Citrus Engineering Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/cec2014-5801.
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Air curtains have long been used to reduce losses from high traffic doorways in cold storage facilities. Different varieties of air curtains have been used including vertical (down blast) non-recirculatory, horizontal non-recirculatory and horizontal recirculatory. The effectiveness of air curtains to provide thermal separation between rooms of differing temperatures has long been a matter of debate. Previous experiments have been done to determine the effectiveness using tracer gas decay methods. This paper will evaluate the thermal effectiveness of the horizontal recirculatory air curtain when applied in a typical cooler application using an environmental chamber. This allowed testing of the air curtain’s ability to reduce infiltration on the actual thermal envelope. A vertical non-recirculatory air curtain was also evaluated for comparison purposes. The air curtains were tested in an environmental chamber that was divided into two rooms of differing temperature. The chamber was instrumented to measure all energy transfer into and out of each room. The cold room was maintained at a temperature of 4°C (39°F) and the warm room was maintained at a temperature of 24°C (75°F) and 60% RH throughout all tests. Three phases of testing were conducted for each air curtain to completely evaluate all energy losses — a completely closed doorway test for calibration, a completely open doorway test with no air curtains and an open doorway test with the air curtains adjusted and running. Completion of the testing revealed the horizontal recirculatory air curtain had a thermal efficiency of 71% while the vertical non-recirculatory air curtain had an efficiency of 38%. The results were slightly lower than theoretical calculations which may be attributable to chamber size. Additional tests were conducted using a smaller doorway for comparison. Applying the results from the smaller doorway yields an effectiveness of 76.2%. Using the theoretical open doorway energy loss yields an effectiveness of 80%. Paper published with permission.
Raporty organizacyjne na temat "PERMISSIONS COMPARISON"
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Watkins, Chris B., Susan Lurie, Amnon Lers i Patricia L. Conklin. Involvement of Antioxidant Enzymes and Genes in the Resistance Mechanism to Postharvest Superficial Scald Development. United States Department of Agriculture, grudzień 2004. http://dx.doi.org/10.32747/2004.7586539.bard.
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The objective of this research project was to evaluate the involvement of antioxidant enzymes and genes in the resistance mechanism to postharvest superficial scald development using two primary systems: 1. Resistant and susceptible progenies of an apple cross between a scald resistant crab apple, ‘White Angel’ and a scald susceptible cultivar, ‘Rome Beauty’; 2. Heat-treatment of ‘Granny Smith’, which is known to reduce scald development in this cultivar. In 2002 we asked for, and received (October 14), permission to revise our initial objectives. The US side decided to expand their results to include further work using commercial cultivars. Also, both sides wanted to include an emphasis on the interaction between these antioxidant enzymes and the á-farnesene pathway, with the cooperation of a third party, Dr. Bruce Whitaker, USDA-ARS, Beltsville. Background: Superficial scald is a physiological storage disorder that causes damage to the skin of apple and pear fruit. It is currently controlled by use of an antioxidant, diphenylamine (DPA), applied postharvest by drenching or dips, but concern exists about such chemical usage especially as it also involves application of fungicides. As a result, there has been increased emphasis on understanding of the underlying mechanisms involved in disorder development. Our approach was to focus on the oxidative processes that occur during scald development, and specifically on using the two model systems described above to determine if the levels of specific antioxidants and/or antioxidant enzyme activities correlated with the presence/absence of scald. It was hoped that information about the role of antioxidant-defense mechanisms would lead to identification of candidate genes for future transgenic manipulation. Major conclusions, solutions, achievements: Collectively, our results highlight the complexity of superficial scald developmental processes. Studies involving comparisons of antioxidant enzyme activities in different crab apple selection, commercial cultivars, and in response to postharvest heat and 1-methylcyclopropene (1-MCP) treatments, show no simple direct relationships with antioxidant contents and susceptibility of fruit to scald development. However, a correlative relationship was found between POX activity or isoenzyme number and scald resistance in most of the studies. This relationship, if confirmed, could be exploited in breeding for scald resistance. In addition, our investigations with key genes in the á-farnesenebiosynthetic pathway, together with antioxidant processes, are being followed up by analysis of exposed and shaded sides of fruit of cultivars that show different degrees of scald control by 1-MCP. These data may further reveal productive areas for future research that will lead to long term control of the disorder. However, given the complexity of scald development, the greatest research need is the production of transgenic fruit with down-regulated genes involved in á- farnesene biosynthesis in order to test the currently popular hypothesis for scald development.