OPTIMASI GEOMETRI ROTATING DISK GUNA MINIMASI TEGANGAN GESER MAKSIMUM DAN TEGANGAN VON-MISSES

Rotating Disk mempunyai beberapa parameter di dalam pembuatannya, salah satunya adalah radius, berat dan ketebalan. Analisa distribusi tegangan pada rotating disk telah lama menjadi masalah dalam teori elastisitas. Untuk menghasilkan efisiensi kerja yang baik pada rotating disk, diperlukan ketepatan dalam perhitungan dan pembuatan desain bentuk. Pada tugas akhir ini profil rotating disk dengan ketebalan bervariasi akan dioptimasi dengan objective function meminimalkan tegangan geser maksimum dan tegangan von-misses. Design variables yang akan dioptimasi adalah ketebalan dan radius. Optimasi adalah suatu metode yang digunakan untuk mencari nilai optimum yang terbaik dari desain yang sudah ada dengan kondisi batas tertentu. Proses optimasi dilakukan secara numerik menggunakan program bantu Matlab, yang ditampilkan dalam bentuk kurva isomerik dengan berbagai variasi variabel desain. Spesifikasi disk yang akan dioptimasi mempunyai 4 segmen dengan diameter 12 inch, density = 0.283 lb/inch3, Yield Strength = 36 kpsi. Dengan kondisi batas Lmin = 0.6 inch, Lmax = 3 inch dan R2>R3>R4>R5>R6. Hasil optimasi berupa tegangan geser maksimum optimal sebesar 1445 psi dan tegangan von-misses optimal sebesar 2548 psi. Kata kunci : Rotating Disk, Tegangan Geser Maksimum, Von-misses

Autologous chondrocyte implantation in the knee : systematic review and economic evaluation

Background: The surfaces of the bones in the knee are covered with articular cartilage, a rubber-like substance that is very smooth, allowing frictionless movement in the joint and acting as a shock absorber. The cells that form the cartilage are called chondrocytes. Natural cartilage is called hyaline cartilage. Articular cartilage has very little capacity for self-repair, so damage may be permanent. Various methods have been used to try to repair cartilage. Autologous chondrocyte implantation (ACI) involves laboratory culture of cartilage-producing cells from the knee and then implanting them into the chondral defect. Objective: To assess the clinical effectiveness and cost-effectiveness of ACI in chondral defects in the knee, compared with microfracture (MF). Data sources: A broad search was done in MEDLINE, EMBASE, The Cochrane Library, NHS Economic Evaluation Database and Web of Science, for studies published since the last Health Technology Assessment review. Review methods: Systematic review of recent reviews, trials, long-term observational studies and economic evaluations of the use of ACI and MF for repairing symptomatic articular cartilage defects of the knee. A new economic model was constructed. Submissions from two manufacturers and the ACTIVE (Autologous Chondrocyte Transplantation/Implantation Versus Existing Treatment) trial group were reviewed. Survival analysis was based on long-term observational studies. Results: Four randomised controlled trials (RCTs) published since the last appraisal provided evidence on the efficacy of ACI. The SUMMIT (Superiority of Matrix-induced autologous chondrocyte implant versus Microfracture for Treatment of symptomatic articular cartilage defects) trial compared matrix-applied chondrocyte implantation (MACI®) against MF. The TIG/ACT/01/2000 (TIG/ACT) trial compared ACI with characterised chondrocytes against MF. The ACTIVE trial compared several forms of ACI against standard treatments, mainly MF. In the SUMMIT trial, improvements in knee injury and osteoarthritis outcome scores (KOOSs), and the proportion of responders, were greater in the MACI group than in the MF group. In the TIG/ACT trial there was improvement in the KOOS at 60 months, but no difference between ACI and MF overall. Patients with onset of symptoms < 3 years’ duration did better with ACI. Results from ACTIVE have not yet been published. Survival analysis suggests that long-term results are better with ACI than with MF. Economic modelling suggested that ACI was cost-effective compared with MF across a range of scenarios. Limitations: The main limitation is the lack of RCT data beyond 5 years of follow-up. A second is that the techniques of ACI are evolving, so long-term data come from trials using forms of ACI that are now superseded. In the modelling, we therefore assumed that durability of cartilage repair as seen in studies of older forms of ACI could be applied in modelling of newer forms. A third is that the high list prices of chondrocytes are reduced by confidential discounting. The main research needs are for longer-term follow-up and for trials of the next generation of ACI. Conclusions: The evidence base for ACI has improved since the last appraisal by the National Institute for Health and Care Excellence. In most analyses, the incremental cost-effectiveness ratios for ACI compared with MF appear to be within a range usually considered acceptable. Research is needed into long-term results of new forms of ACI

OPTIMASI GEOMETRI ROTATING DISK BERTINGKAT UNTUK MEMINIMALKAN TEGANGAN TANGENSIAL MAKSIMUM DAN RATA-RATA MENGGUNAKAN MATLAB

Banyak elemen mesin yang dapat dimodelkan sebagai benda solid simetris terhadap sumbunya (axissymmetric) yang berputar, salah satu contohnya yaitu piringan berputar (rotating disk). Analisa distribusi tegangan pada rotating disk telah lama menjadi masalah dalam teori elastisitas. Permasalahannya adalah pada besar dan distribusi tegangan sebagai faktor pembatas utama pada mesin yang berputar cepat, yang menyebabkan kegagalan dari elemen mesin ini. Pada tugas akhir ini akan profil rotating disk akan dioptimasi dengan objective function meminimalkan tegangan tangensial maksimum dan rata-rata dalam batasan tertentu. Proses optimasi dilakukan secara numerik menggunakan program Matlab, hasil optimasi ditampilkan dalam bentuk kurva isomerit dengan berbagai variabel desain. Kata kunci : Rotating Disk, Optimasi, Tegangan Tangensial, Isomerit, Matla

Routine development of objectively derived search strategies

BACKGROUND:Over the past few years, information retrieval has become more and more professionalized and information specialists are considered full members of a research team conducting systematic reviews. Research groups preparing systematic reviews and clinical practice guidelines have been the driving force in the development of search strategies, but open questions remain regarding the transparency of the development process and the available resources. An empirically guided approach to the development of a search strategy provides a way to increase transparency and efficiency.METHODS:The aim of this paper is to describe the empirically guided development process for search strategies as applied by the German Institute for Quality and Efficiency in Health Care (Institut fur Qualitat und Wirtschaftlichkeit im Gesundheitswesen, IQWiG). This strategy consists of the following steps: generation of a test set, as well as development, validation, and standardized documentation of the search strategy.RESULTS:We illustrated our approach by means of an example, i.e. a search for literature on brachytherapy in patients with prostate cancer. For this purpose, a test set was generated including a total of 38 references from 3 systematic reviews. The development set for the generation of the strategy included 25 references. After application of text-analytic procedures a strategy was developed including all references of the development set. In order to test the search strategy on an independent set of references, the remaining 13 references from the test set (validation set) were used; the validation set was also completely identified.DISCUSSION:Our conclusion is that an objectively derived approach, similar to that used in search filter development, is a feasible way to develop and validate reliable search strategies. Besides creating high-quality strategies, the widespread application of this approach would result in a substantial increase in the transparency of the development process of search strategies