Karakteristik Bahan Dasar Diesel Cylinder Liner (Dcl)

Kebutuhan Diesel Cylinder Liner(DCL) di Indonesia 114.512 buah DCL/hari untuk mendukung industry transportasi di Indonesia. Kebutuhan DCL yang tinggi tersebut, saat ini suplainya masih didominasi dari luar negeri. Industry pengecoran besi cor local sudah mencoba produksi DCL, akan tetapi kualitas DCL yang dihasilkan masih jauh dari standar. Penelitian ini bertujuan untuk mengetahui karakteristik komposisi kimia, kekerasan brinell, dan struktur mikro dari 3 jenis DCL yang beredar di industry transpotasi yaitu original merk X, tidak original, dan produk pengecoran local, sehingga dapat diketahui kualitas rendah DCL produksi local dikarenakan kualitas bahan atau factor yang lain. Hasil pengujian menunjukkan bahan dasar yang digunakan DCL produksi local menggunakan jenis besi cor yang sama dengan DCL originalya itu besi cor kelabu. Hasil pengujian kekerasan menunjukkan bahwa DCL produksi local memiliki kekerasan tertinggi yaitu 217,9 HBN, sedangkan DCL original dengan DCL tidak original menunjukkan nilai yang hamper sama yaitu 187,6 HBN dan 185,2 HBN. Hasil pengujian menunjukkan bahwa struktur mikro semua jenis DCL menunjukan struktur pearlite dan grafit (bentuk flake dengan orientasi tak beraturan) mendominasi seluruh permukaan. Katakunci: DCL, komposisikia, kekerasan, struktur mikr

Improved control strategy of DFIG-based wind turbines using direct torque and direct power control techniques

This paper presents different control strategies for a variable-speed wind energy conversion system (WECS), based on a doubly fed induction generator. Direct Torque Control (DTC) with Space-Vector Modulation is used on the rotor side converter. This control method is known to reduce the fluctuations of the torque and flux at low speeds in contrast to the classical DTC, where the frequency of switching is uncontrollable. The reference for torque is obtained from the maximum power point tracking technique of the wind turbine. For the grid-side converter, a fuzzy direct power control is proposed for the control of the instantaneous active and reactive power. Simulation results of the WECS are presented to compare the performance of the proposed and classical control approaches.Peer reviewedFinal Accepted Versio

Présentation atypique d’une granulomatose avec polyangeite: à propos d’une observation pédiatrique

La granulomatose avec polyangéite (GPA) est une vascularite nécrosante systémique, caractérisée par une inflammation granulomateuse, une nécrose tissulaire et une vascularite touchant les vaisseaux de moyen et, surtout, de petit calibre, elle touche rarement l'enfant

Porokeratosis: Two Faces, One Family

Porokeratosis is a disorder of keratinisation whose pathogenesis is yet unclear. It has been postulated that it results from the proliferation of an abnormal clone of keratinocytes, triggered by several factors, such as immunosuppression or prolonged ultraviolet exposure. Various clinical forms are recognized whose common denominator is a keratotic ring surrounding a central zone of atrophy. The histological hallmark is the cornoid lamella, a thin column of hyperproliferative abnormal keratinocytes. We describe two cases of porokeratosis. A 67-year-old woman with an erythematous purplish round plaque surrounded by a keratotic border that had appeared 6 years previously on the left sural region was diagnosed as ‘giant’ porokeratosis. A 49-year-old man presented with small papules coalescent in an erythematous oval plaque on the lateral side of the left foot consistent with linear porokeratosis

Effects of the substitution in the two sites on barium titanate properties

Barium titanate compound has been studied given their many interesting physico-chemical properties, including their dielectric and ferroelectric behavior. Besides, the introduction of different elements in the barium titanate matrix increases the number of applications in which these compounds can be used. Within this context, in the present work we investigated the effect of doping barium titanate with alkali ions (Ca) and rare earth ions (Er) in Ba sites and by tin ions in Ti sites. The synthesized compound, termed BETS-Ca, was prepared via a solid–solid reaction technique. X-ray diffraction measurements indicated that the material has a tetragonal symmetry structure. Scanning electron microscopy analysis allowed to identify a dense microstructure with the existence of both grain and grain boundaries. Moreover, optical absorbance and infrared spectra indicated the incorporation of doping elements such as erbium and tin. Additionally, the electric and dielectric properties of the compounds were investigated. AC conductivity analysis suggested that conduction is governed by correlated barriers hopping and non overlapping small polaron tunneling processes. Nyquist plot showed the contribution of both grain and grain boundaries to the conduction. Finally, a ferroelectric-paraelectric transition was found around a specific temperature (TC = 360 K). According to the Curie-Weiss law, this transition has a diffusive characte

Mucocele geante de l’enfant

Les mucocèles sont des formations pseudo kystiques expansives des sinus de la face. Elles sont souvent diagnostiquées tardivement du fait de l’absence de signes spécifiques. Le bilan radiologique basé sur la TDM et ou l’IRM est essentiel pour confirmer le diagnostic et établir le bilan d’extension. Nous rapportons le cas d’un enfant âgé de 4 ans et 6mois traité d’une mucocèle géante éthmoïdo- maxillaire.Mots clés : mucocèle ; enfant ; TDM ; IRM ; chirurgieMucoceles are pseudo-cystic expansive formations of the sinuses. They are often diagnosed lately because of the lack of specific signs. CT and MRI are essential for the diagnosis and to evaluate the extension.We report a case of child with ethmoide-maxillary mucocèle treated in our department.Key words: mucocele; child; CT; MRI; surger

Updating the distribution of American black bears (\u3cem\u3eUrsus americanus\u3c/em\u3e) in Texas using community science, state agencies, and natural history collections

The American black bear (Ursus americanus) is one of largest terrestrial mammals found in Texas. Despite the black bear’s large size and charismatic nature, its distribution across the state has been difficult to determine due to outdated distribution maps. Although recent sighting reports indicate that the current distribution of black bears in Texas may be expanding in some areas, researching changes in black bear populations can be difficult and cost prohibitive. Data from community science initiatives and natural history collections can be useful to better understand species distributions and ecology. We used records from Texas Parks and Wildlife Department, iNaturalist, and VertNet to describe the distribution of U. americanus in Texas. Our results indicate that black bears may not be widely distributed across Texas and may be breeding in only a small number of counties. Our study highlights the usefulness of successful community science programs and the long-term historical importance of natural history collection records and natural resource agency data sets in better understanding geographic distributions of various species, including U. americanus. These initiatives paired with improved communication and collaboration between natural history collections, community scientists, and municipal, state, and federal natural resource and wildlife agencies can provide valuable information for a variety of species and facilitate future research.El oso negro americano (Ursus americanus) es uno de los mamíferos terrestres de mayor tamaño en Texas. A pesar de su gran tamaño y naturaleza carismática, la distribución actual del oso negro a lo largo del estado de Texas ha sido difícil determinar debido a mapas de distribución obsoletos. Aunque los reportes recientes de avistamientos sugieren que las poblaciones de oso negro se están expandiendo en algunas áreas de Texas la investigación formal de cambios poblacionales es logísticamente compleja y costosa. En este sentido, los datos derivados de las iniciativas de ciencia comunidad y de las colecciones de historia natural pueden ser de gran utilidad para mejorar el conocimiento sobre la distribución y ecología de las especies. En el presente estudio utilizamos datos de los registros del Departamento de Parques y Vida Silvestre de Texas, iNaturalist y VertNet para definir la distribución del U. americanus en Texas. Nuestros resultados indican que el oso negro no parece tener una presencia amplia en muchas áreas de Texas y es probable que solo se esté reproduciendo en un pequeño número de condados. Nuestro estudio destaca la utilidad de los programas de ciencia comunidad exitosos, así como la importancia histórica a largo plazo de los registros de los museos y de las bases de datos de las agencias gubernamentales para comprender mejor las distribuciones geográficas de varias especies, incluido U. americanus. Estas iniciativas, acompañadas de una mejor comunicación y colaboración entre museos de historia natural, científicos comunidad y agencias de recursos naturales y vida silvestre a nivel municipal, estatal y federal, pueden proveer de información valiosa sobre diversas especies y facilitar investigación a futuro