Waseda University

About: Waseda University is a education organization based out in Tokyo, Japan. It is known for research contribution in the topics: Catalysis & Large Hadron Collider. The organization has 24220 authors who have published 46859 publications receiving 837855 citations. The organization is also known as: Waseda daigaku & Sōdai.

A proposal on digital watermark in document image communication and its application to realizing a signature

Abstract: With the advance of telematic technology, increasing document image information utilized in the state of soft copy is expected. In these situations, copies of obtained document image information are made illegally with ease, and hence the validity authentication of the information itself and its provider becomes more necessary. Since document image information to be authenticated exists in a form which can be read at an unidentified number of receiver terminals, the realization of an authentication scheme where document image and signature are combined is necessary. This is characteristic of document image information including nature pictures and photographs. This paper proposes a new concept of signature, which is called “digital watermark” for document image communication. A digital watermark is the coding scheme in which secret information is embedded into a document image similar to a watermark. Image coding schemes already proposed are available to realize a digital watermark. We present a method of obtaining a digital watermark using a well-known predictive coding algorithm. Also, we define a criterion for security and show to what extent the digital signature is safe using simulation results, where two or three illegal actions are considered.

Conversion of dry gel to microporous crystals in gas phase

Abstract: Recently the dry gel conversion (DGC) technique, where a hydrogel is dried and the resultant dry gel is converted into microporous crystals in steam or in a mixed vapor of steam and organic structure-directing agents (SDAs), has been developed. It has been shown that a wide variety of microporous crystals, pure silica microporous crystals, aluminosilicates, metallosilicates, and aluminophosphates, can be synthesized using the DGC method. Remarkable results have been reported in the synthesis of BEA types zeolites, namely aluminosilicate, titaniumsilicate, zincosilicate, and borosilicate with BEA topology, using tetraethylammonium hydroxide, a commercially available SDA. It has also been found that zeolite OU-1, probably analogous to SSZ-31 and NCL-1, is formed via phase transformation from BEA. Dense zeolite coatings like membranes are possible using this method. Characteristics of the DGC method are discussed in detail.