Performance measurement and evaluation of time-shared operating systems

Time-shared, virtual memory systems are very complex and changes in their performance may be caused by many factors - by variations in the workload as well as changes in system configuration. The evaluation of these systems can thus best be carried out by linking results obtained from a planned programme of measurements, taken on the system, to some model of it. Such a programme of measurements is best carried out under conditions in which all the parameters likely to affect the system's performance are reproducible, and under the control of the experimenter. In order that this be possible the workload used must be simulated and presented to the target system through some form of automatic workload driver. A case study of such a methodology is presented in which the system (in this case the Edinburgh Multi-Access System) is monitored during a controlled experiment (designed and analysed using standard techniques in common use in many other branches of experimental science) and the results so obtained used to calibrate and validate a simple simulation model of the system. This model is then used in further investigation of the effect of certain system parameters upon the system performance. The factors covered by this exercise include the effect of varying: main memory size, process loading algorithm and secondary memory characteristics

Virtual files: a Framework for Experimental Design

The increasing power and decreasing cost of computers has resulted in them being applied in an ever widening area. In the world of Computer Aided Design it is now practicable to involve the machine in the earlier stages where a design is still speculative, as well as in the later stages where the computer's calculating ability becomes paramount. Research on database systems has not followed this trend, concentrating instead on commercial applications, with the result that there are very few systems targeted at the early stages of the design process. In this thesis we consider the design and implementation of the file manager for such a system, first of all from the point of view of a single designer working on an entire design, and then from the point of view of a team of designers, each working on a separate aspect of a design. We consider the functionality required of the type of system we are proposing, defining the terminology of experiments to describe it. Having ascertained our requirements we survey current database technology in order to determine to what extent it meets our requirements. We consider traditional concurrency control methods and conclude that they are incompatible with our requirements. We consider current data models and conclude that, with the exception of the persistent programming model, they are not appropriate in the context required, while the implementation of the persistent programming model provides transactions on data structures but not experiments. The implementation of experiments is considered. We examine a number of potential methods, deciding on differential files as the one most likely both to meet our requirements and to have the lowest overheads. Measurements conducted on both a preliminary and a full-scale implementation confirm that this is the case. There are, nevertheless, further gains in convenience and performance to be obtained by exploiting the capabilities of the hardware to the full; we discuss these in relation to virtual memory systems, with particular reference to the VAX/VMS environment. Turning to the case where several designers are each working on a (nearly) distinct part of a design, we consider how to detect conflicts between experiments. Basing our approach on optimistic concurrency control methods, we show how read and write sets may be used to determine those areas of the database where conflicts might arise. As an aside, we show how the methods we propose can be used in an alternative approach to optimistic concurrency control, giving a reduction in system overheads for certain applications. We consider implementation techniques, concluding that a differential files approach has significant advantages in maintaining write sets, while a two-level bitmap may be used to maintain read sets efficiently

Analisis Pasar Saham Syariah Jakarta Islamic Index (JII) pada Pelantikan Gubernur DKI Jakarta Anies Baswedan terhadap Abnormal Return

ABSTRAK Rahman Anugrah Agung Putra (2019) : Analisis Pasar Saham Syariah Jakarta Islamic Index (JII) pada Pelantikan Gubernur DKI Jakarta Anies Baswedan terhadap Abnormal Return Tujuan dari penelitian ini yaitu untuk menguji reaksi pasar modal terhadap rata-rata abnormal return, sebelum, saat, dan setelah pelantikan Gubernur DKI Jakarta. Penelitian ini tergolong penelitian event study dengan pendekatan market adjusted-model. Populasi dalam penelitian ini adalah seluruh perusahaam yang terdaftar di BEI pada Oktober 2017. Sampel dalam penelitian ini adalah 45 perusahaan yang diperolah dengan menggunakan teknik purposive sampling dengan kriteria yaitu seluruh perusahaan yan tergabung dalam Index LQ-45. Teknik analisis data untuk pengujian hipotesis dalam penelitian ini adalah Paired Sample T-tes dan Wilcoxon Signed Rank dengan menggunakan alat analisis yaitu SPSS 21. Hasil pengujian untuk abnormal return menunjukkan Tidak adanya perbedaan rata-rata abnormal return sebelum-saat,saat-setelah, dan sebelum-setelah pelantikan Gubernur DKI Jakarta. Hal ini mengindikasikan bahwa informasi mengenai pelantikan Gubernur DKI Jakarta sudah diserap pasar sebelum peristiwa tersebut terjadi. ini mengindikasikan investor cenderung berhati-hati terhadap aksi yang sedang terjadi serta cenderung melakukan strategi wait and see. Kata Kunci: Pasar Modal, Pelantikan Gubernur DKI Jakarta, Abnormal Retur

KLASIFIKASI TWEET BERDASARKAN TOPIK BERITA DENGAN METODE SUPPORT VECTOR MACHINE (SVM)

Twitter adalah layanan jaringan sosial media yang memungkinkan penggunanya untuk mengirim dan membaca pesan berbasis teks hingga 140 karakter, yang dikenal dengan kicauan (tweet). Tweets yang muncul pada beranda Twitter tergabung menjadi satu tanpa ada pengelompokkan kategori seperti ekonomi, olahraga, teknologi, otomotif dan kesehatan. Permasalahan yang muncul adalah pengguna menjadi kesulitan untuk memilah berita atau informasi yang diinginkan. Maka, berdasarkan tweets yang bercampur aduk tersebut dapat diklasifikasikan berdasarkan kategorinya untuk memudahkan ketika seorang pengguna mencari sebuah berita atau informasi yang diinginkan. Twitter juga dapat membantu pengguna Twitter menemukan topik yang menarik bagi mereka. Oleh karena itu, klasifikasi tweet berdasarkan topik berita perlu dilakukan dengan metode Support Vector Machine (SVM). Penelitian ini menggunakan 5000 data tweet sebagai dataset. Untuk menggantikan proses pelabelan manual, menjadi pelabelan otomatis untuk skala besar. Tahapan yang dibutuhkan untuk mengetahui akurasi yang dihasilkan SVM dalam mengklasifikasikan tweet berdasarkan topik berita yaitu: pelabelan manual, preproccesing, seleksi fitur dan proses pembelajaran SVM. Penelitian ini menggunakan pembagian data 90% sebagai data latih dan 10% sebagai data uji. Model pembelajaran yang dihasilkan SVM, didapat sebesar 96.2% dengan threshold 3 dan menggunakan ∁ = 8 dan Gamma = 0.0005. Kata Kunci: Klasifikasi, Minat, Preprocessing, Support Vector Machine, Topik berita, Twee

Applications of Mathematical Models in Engineering

The most influential research topic in the twenty-first century seems to be mathematics, as it generates innovation in a wide range of research fields. It supports all engineering fields, but also areas such as medicine, healthcare, business, etc. Therefore, the intention of this Special Issue is to deal with mathematical works related to engineering and multidisciplinary problems. Modern developments in theoretical and applied science have widely depended our knowledge of the derivatives and integrals of the fractional order appearing in engineering practices. Therefore, one goal of this Special Issue is to focus on recent achievements and future challenges in the theory and applications of fractional calculus in engineering sciences. The special issue included some original research articles that address significant issues and contribute towards the development of new concepts, methodologies, applications, trends and knowledge in mathematics. Potential topics include, but are not limited to, the following: Fractional mathematical models; Computational methods for the fractional PDEs in engineering; New mathematical approaches, innovations and challenges in biotechnologies and biomedicine; Applied mathematics; Engineering research based on advanced mathematical tools