Judul: The Decrease of Freeriding Effect to the Resource Providers in Peer-to-Peer File Sharing System with Social Network Information
Abstrak: Freeriders only use system resources without sharing any resources to others or sharing re-sources which are not used by the system. This behavior is one significant problem that needs to be considered in improving the quality of P2P file sharing system. Moreover, it can lead the system to lack of quality resources, and hence, its performance will gradually decrease and further possibly collapse. Many studies raised concern on how social network information can reduce this behavior and improve the system performance. This research applies social network information by using a SocialGnutella algorithm to P2P file sharing system. The algorithm is simulated to observe how the system used to numerous peers in the contact list. This simulation used 512 and 1024 peers with each peer having five transactions and 30 repetitions in merge. Available bandwidth and utility of resource provider used to measure the system performance during the simulation. From the simulation, average utility of resource providers in the system using social network information reached 0.959 and 0.979 for 512 and 1024, respectively. Whereas in the system which is not used social network information reached 0.527 and 0.531. Average utility is significantly higher based on the t-test result at 99.9% confidence level. Hence, system which is used social network information can decrease the freeriding behaviour and directly impact the resource provider.
Keyword: peer-to-peer file sharing system, social network information, SocialGnutella, available bandwidth of resource providers, utility of resource providers

Judul: Implementasi Jaringan Peer-to-Peer Tak Terstruktur Menggunakan Protokol JXTA
Abstrak: Internet is useful for communication, exchanging information, and businesses. Most internet network is based on client-server system, which is a centralized network. The server acts as the center of network and has the ability to transfer data as requested by the client. In a client-server system, the network will be down if the server is busy or interrupted. This disadvantage can be solved by Peer-to-Peer (P2P) network. In P2P network, client or “peer” can communicate with other peers without relying on the server. One of the P2P network protocols is JXTA protocol, an open source protocol that can connect mobile devices or computers to P2P network. The objective of this research was to implement the unstructured P2P application by using JXTA protocol and additional peer group. In this research, the features of investigated P2P application were chatting within peer group, searching for files, and downloading files. It was found that these features can only be performed by peers that were directly connected to other peers in the same subnet. Furthermore, this research showed that the highest percentage of overhead file was 10.13% and the percentage of overhead protocol did not exceed 0.5%
Keyword: 

Judul: Codiaeum Malesia
Abstrak: The Malesian genus Codiaeum has been revised based on the morphological character using available herbarium collections in Herbarium Bogor iense and loan specimens from Rijksherbarium Leiden. The study is based on the observation of 350 specimens. Eleven species have been recognized, namely Codiaeum variegatum, C. luzonicum, C. palawanense, C. trichocalyx, C. megalanthum, C. cilliatum, C. affine, C. tenerifolium dan C. hirsutum, C. macgregorii, C. ludovicianum. number of species is found in the Philippines The highest (8 species), Two species (C. tenerifolium and C. ludovicianum) endemic in Lousiade Archipelago of the New Guinea and C. affine endemic in Banguey Island. C. variegatum is widespread by nature or in cultivation almost in all of Malesian region. C. cillia tum is a species in the earliest level among the other species according to 20 selected characters.
Keyword: Codiaeum, Malesia