High-bandwidth controller design for dual-stage actuator system in hard disk drives

Large-capacity hard disk drives are important for the development of an information society. The capacities of hard disk drives depend on the positioning accuracy of magnetic heads, which read and write digital data, in disk-positioning control systems. Therefore, it is necessary to improve positioning accuracy to develop hard disk drives with large capacities. Hard disk drives employ dual-stage actuator systems to accurately control the magnetic heads. A dual-stage actuator system consists of a voice coil motor and micro-actuator. In micro-actuators, there is a trade-off between head-positioning accuracy and stroke limitation. In particular, in a conventional controller design, the micro-actuator is required to actuate such that it compensates for low-frequency vibration. To overcome this trade-off, this study proposes a high-bandwidth controller design for the micro-actuator in a dual-stage actuator system. The proposed method can reduce the required stroke of the micro-actuator by increasing the gain of the feedback controller of the voice coil motor at low frequencies. Although the voice coil motor control loop becomes unstable, the micro-actuator stabilizes the entire feedback loop at high frequencies. As a result, the control system improves the positioning accuracy compared to that achieved by conventional control methods, and the required micro-actuator stroke is reduced.

The Effect of Wear Rate on Polymeric Composites Reinforced Nanoclays

This research aims to study the addition of nanoclays on unsaturated polyester (UP) and epoxy resin (EP) as filling and by weight percentage (2%, 4% and 6%) to this mixture and then study the extent of the effect of this addition on wear rate of the composites’ material where three loads were adopted (10, 15 and 20[Formula: see text]N), respectively, on the iron hard disk (269 HB) and copper hard disk of 111[Formula: see text]HB for the resin before and after adding the clays, where the approved sliding velocities were 4.1887, 3.1415 and 2.0943[Formula: see text]m/sec, respectively, and the test duration was 10 min on the test disc. Immersion of samples in the water for 2, 4, 6 and 8 weeks showed a clear improvement in the wear rate and tear values of dry and submerged conditions in a water under different conditions of load change, slipping speed, time and temperature stability after adding the nanoclays to the polymer.

Spesifikasi Kebutuhan Perangkat Lunak Sistem Informasi Berita Dengan Standard ISO/IEC/IEEE 29148:2018

TVRI Sulawesi Tengah merupakan lembaga yang bergerak dibidang penyiaran publik, serta mempunyai tugas untuk memberikan pelayanan informasi, pendidikan, hiburan yang sehat, kontrol dan perekat sosial. Memiliki siaran lokal yang beragam membuat TVRI Sulawesi Tengah dituntut untuk update dalam memberikan informasi setiap harinya. Kenyataannya dalam aktivitas sehari-hari, pendistribusian naskah dan list berita masih dilakukan secara manual yaitu mengandalkan Microsoft Word dan Microsoft Excel serta pendistribusian item berita yang berisikan video atau gambar hasil liputan reporter dan kameramen yang sudah di edit dengan menambahkan hasil dubbing dari dubber di distribusikan mengandalkan hard disk yang sewaktu-waktu bisa terserang virus dan akhirnya data yang di dalam tidak dapat terbaca oleh komputer. Oleh karena itu untuk memudahkan proses operasional, diperlukan analisis kebutuhan perangkat lunak sistem informasi berita untuk menganalisis kebutuhan dari perangkat lunak sistem informasi yang diperlukan sesuai dengan proses bisnis yang sedang berlangsung. Analisis kebutuhan perangkat lunak sistem informasi berita ini menggunakan outline dari Software Requirements Specification standar ISO/IEC/IEEE 29148:2018. Analisis kebutuhan yang dilakukan menghasilkan enam (6) menu antara lain tambah naskah baru, review naskah, data naskah, list berita, data list berita, gambar berita, data gambar berita dan siaran siap tayang.

Mathematical modeling of contact interaction of two electroelastic half-spaces (without electrode coating of surfaces) in the presence of a hard disk-like inclusion between them and pressure in the area of separation

Based on the use of a rigorous mathematical model that takes into account the connectivity of force and electric fields in electroelastic bodies, the contact interaction of two piezoelectric transversely isotropic half-spaces with different properties under compression (in the presence of a hard disk-shaped inclusion between them and pressure in the material separation region) was studied. The solution to the problem is obtained by representing the general solution of the static equations of the electroelasticity for a transversely isotropic body in terms of harmonic functions, followed by the construction of the boundary value problem of the electroelasticity to the consideration of the integral equation and the expansion of the desired function in a small parameter. As a special case from the constructed analytical expressions, the main parameters of the contact for two elastic transversely isotropic and isotropic half-spaces (with the inclusion between them and pressure in the separation region) are implied. Numerical results were obtained. The influence was studied of the electroelastic properties of half-spaces, the geometric dimensions of the inclusion, and loads on the parameters of the contact interaction of electroelastic bodies.