A Visionary Approach Study about the Member Construction Firms of Turkish Contractors Association (TCA)

In this study Turkish Contractors Association (TCA) members construction fims’ visionary approaches were investigated. A questionnaire has applicated to technical and administrative elements who works in 56 construction firms for evaluation of visionary approach of these firms. In this wise general profile of these firms’ evaluation of visionary approach has been understand and which firms emphasize which characteristics in determine vision investigated. Acquired by findings; these firms emphasizes their quality, trust and technologies in first three; their tangibility, being polyhedral and sensuality followed them. These fims’ emphasis to quality ratios were 64.3%, emphasis on job security were 32.1% and environmental stres ratio were 35.7% in their visions. Turkish construction firms have to create and applicate the most appropriate strategies for being successfull in global competitive race and to carry that success into long term. Our companies’ competitive advantage by providing with a strategic advantage are associeted with their visions

Tıbbi Ortamlarda Kullanılan Portatif Hava Temizleme Sistemi

Toplum içerisinde ortak kullanıma açık alanlarda hava kalitesinin korunması sağlık açısından önemlidir ve güncel bir problemdir. Bu problem, havalandırmanın yetersiz olduğu birçok ortak kullanım alanı ile birlikte büyük veya küçük sağlık hizmeti veren kuruluşlarda kendini sıklıkla salgın hastalıklarla ya da yaşanan ölümler ile göstermektedir. Bu problemin önüne geçilebilmesi için bu zamana kadar atılan adımlar yetersiz kalabilmektedir. Çalışma kapsamında, partikül tutucu filtreler, UV lambalar kullanılarak, küçük ve taşınabilir, medikal seviyede hava kalitesi sağlayan bir hava temizleme sistemin tasarlanmıştır. Bu sistem EN ISO 14644-1 temiz oda standartlarına uygun olacak şekilde UV-C teknolojisinden yararlanılarak tasarlanmıştır. Bu cihaz, sağlık kuruluşlarındaki toplu taşıma araçları, bekleme ve yoğun bakım odaları, mikrobiyoloji ve biyokimya laboratuvarları gibi yerlerde kullanılabilir niteliktedir

The Effect of the Rate of Waste Tire Powder Substitution on the Physical and Mechanical Properties of CEM II Cement

Recycling of waste has a great importance in preservation of the energy and decreasing the global impact that has been created by production of new materials. There is an increasing debate about the use of waste tires because of their environmental and health affects. Waste tires can be used for a range of civil engineering applications. This study investigates the physical and mechanical properties of CEM II (reference) and waste tire powder substituted cements. For this purpose, waste tire powder was substituted as a replacement for CEM II cement in amounts of 0, 2.5, 5, 7.5 and 10 weight %. The effects of waste tire powder on compressive and flexural strength, setting time, water demand and volume expansion were determined by standard tests of cement. As a result, a relative increase according to reference cement pastes was determined in the setting time of the waste tire powder substituted cement pastes. Besides these, a decrease were identified with the 2, 7, 28 and 56 days flexural and compressive strength tests for the waste tire powder substituted cement mortars according to reference cement mortars

[BW12O40]^3- ve 2,2'-Bipiridil içeren yeni bir nikel(II) kompleksinin sentezi ve karakterizasyonu

A Keggin-type polyoxometalate {Ni(2,2'-bipy)2(H2O)[BW12O40]}3- (NiBWO) has been hydrothermally synthesized in the high temperature resistant glass bottle for the first time. The structure has been characterized.by elemental analyses, X-ray diffraction, Fourier Transform Infrared Spectroscopy, Thermogravimetric Analysis, Scanning Electron Microscope and X-ray single crystal diffraction analyses. The X-ray single crystal study shows that the asymmetric unit of NiBWO is composed of one [BW12O40] 5- anion, one [Ni(2,2'-bipy)2(H2O)]2+ and one and a half of [Ni(2,2'-bipy)3] 2+ cations.Keggin tipi bir polioksometalat olan {Ni(2,2'-bipy)2(H2O)[BW12O40]}3- (NiBWO) bileşiği yüksek ısıya dayanıklı cam şişede hidrotermal olarak ilk kez sentezlenmiştir. Bileşiğin yapısı elementel analiz, X-ışını kırınımı, Fourier Dönüşümlü Kızılötesi Spektroskopisi, Termogravimetrik Analiz, Taramalı Elektron Mikroskobu ve X-ışını tek kristal kırınım analizleri ile karakterize edilmiştir. X-ışını tek kristal analiz sonucu, NiBWO bileşiğinin asimetrik biriminin bir [BW12O40] 5- anyonu, bir [Ni(2,2'-bipy)2(H2O)]2+ ve bir buçuk [Ni(2,2'-bipy)3] 2+ katyonlarından oluştuğunu göstermiştir

Statistical Analysis of Reduced Round Compression Functions of SHA-3 Second Round Candidates

National Institute of Standards and Technology announced a competition in 2008, of which the winner will be acknowledged as the new hash standard SHA-3. There are 14 second round candidates which are selected among 51 first round algorithms. In this paper, we apply statistical analysis to the second round candidate algorithms by using two different methods, and observe how conservative the algorithms are in terms of randomness. The first method evaluates 256-bit outputs, obtained from reduced round versions of the algorithms, through statistical randomness tests. On the other hand, the second method evaluates the randomness of the reduced round compression functions based on certain cryptographic properties. This analysis gives a rough idea on the security factor of the compression functions

Cryptographic Randomness Testing of Block Ciphers and Hash Functions

One of the most basic properties expected from block ciphers and hash functions is passing statistical randomness testing, as they are expected to behave like random mappings. Previously, testing of AES candidate block ciphers was done by concatenating the outputs of the algorithms obtained from various input types. In this work, a more convenient method, namely the cryptographic randomness testing is introduced. A package of statistical tests are designed based on certain cryptographic properties of block ciphers and hash functions to evaluate their randomness. The package is applied to the AES finalists, and produced more precise results than those obtained in similar applications

İstatiksel rastgelelik testlerinin bütünleşik bir değerlendirmesi ve aralarındaki ilişkilerin deneysel analizi.

Random numbers are used in many applications in our daily life. For instance, when your mobile phone is registering a base station, base station sends a random number for authenticating your phone. Moreover, when logging in your e-mail or bank account your browser and the server exchange random numbers while establishing a handshake. Besides, encryption keys and IVs should be random so that no one can predict them without trying all possible values. The number of examples can be increased from many fields including cryptography, information theory, simulation and quantum theory. Random number sequences are generated by the random number generators (RNG)1 . Deterministic RNGs should be tested to make sure that the output sequences are indistinguishable from random sequences. Unfortunately, theoretic testing is not possible if the output sequences have very obvious relations which is not a usual case. Therefore, testing process is done statistically by applying randomness tests on the sequences and the results are evaluated to conclude the non-randomness of the generator. For the decision to be more reliable a set of tests called test suites are applied on the sequences. Nearly all test suites uses the probabilities derived from the approximations of the distribution functions of the tests. As the approximations work for longer sequences, testing short sequences like keys or IVs becomes infeasible. Moreover, the relations among the tests, which affect the decision on the sequence or the generator, are not measured in any suite. In this thesis, we examine the statistical randomness tests in the literature. We select the tests which are based on mathematical background and are important measures for randomness. Then, we review the distribution functions of these tests to compute the actual probability values. Moreover, we give recursions for the tests whose probability values cannot be computed for longer sequences. Afterwards we find the correlations between the tests and make a classification accordingly. Then, we give some rule of thumbs for designing a test suite and build a test suite consisting of the examined tests. Ph.D. - Doctoral Progra

Özet fonksiyonların tasarımı ve analizi.

Hash functions are cryptographic tools that are used in various applications like digital signature, message integrity checking, password storage and random number generation. These cryptographic primitives were, first, constructed using modular arithmetical operations which were popular at that time because of public key cryptography. Later, in 1989, Merkle and Damgard independently proposed an iterative construction method. This method was easy to implement and had a security proof. MD-4 was the first hash function to be designed using Merkle-Damgard construction. MD-5 and SHA algorithms followed MD-4. The improvements in the construction methods accordingly resulted in improvements and variations of cryptanalytic methods. The series of attacks of Wang et al. on MD and SHA families threaten the security of these hash functions. Moreover, as the standard hashing algorithm SHA-2 has a similar structure with the mentioned hash functions, its security became questionable. Therefore, NIST announced a publicly available contest to select the new algorithm as the new hash standard SHA-3. The design and analysis of hash functions became the most interesting topic of cryptography. A considerable number of algorithms had been designed for the competition. These algorithms were tested against possible attacks and proposed to NIST. After this step, a worldwide interest started to check the security of the algorithms which will continue untill 4th quarter of 2011 to contribute to the selection process. This thesis presents two important aspects of hash functions: design and analysis. The design of hash functions are investigated under two subtopics which are compression functions and the construction methods. Compression functions are the core of the hashing algorithms and most of the effort is on the compression function when designing an algorithm. Moreover, for Merkle-Damgard hash functions, the security of the algorithm depends on the security of the compression function. Construction method is also an important design parameter which defines the strength of the algorithm. Construction method and compression function should be consistent with each other. On the other hand, when designing a hash function analysis is as important as choosing designing parameters. Using known attacks, possible weaknesses in the algorithm can be revealed and algorithm can be strengthened. Also, the security of a hash function can be examined using cryptanalytic methods. The analysis part of the thesis is consisting of various generic attacks that are selected to apply most of the hash functions. This part includes the attacks that NIST is expecting from new standard algorithm to resist.M.S. - Master of Scienc

Characterisation and enumeration of a class of semi-bent quadratic Boolean functions

In this paper, we consider semi-bentness of quadratic Boolean functions defined for even n and give the characterisation of these functions. Up to our knowledge, semi-bentness of this class has not been investigated before and we proved that semi-bent functions of this form exist only for 6|n. Furthermore, we present a method for enumeration of semi-bent and bent functions in certain classes. Using this method we find the exact number of semi-bent functions of this form. Moreover, we complete some previous partial and incomplete enumeration results for three other classes of semi-bent/bent functions in the literature using this method. We also correct some results on quadratic bent functions stated in Ma et al