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Abstrak :

Seismik anisotropi didefinisikan sebagai kecepatan yang bergantung arah dari penjalaran gelombang. Pengetahuan tentang anisotropi pada data seismik sangatlah penting. Fenomena anisotropi disebabkan karena adanya kebervariasian di lapisan yang lebih dangkal dan disebabkan karena propagasi gelombang seismik yang semakin jauh pada ofset yang jauh. Koreksi NMO mengunakan pendekatan konvensional hiperbolik pada media anisotropi masih kurang maksimal dan masih memperlihatkan adanya fenomena hockey stick pada ofset yang jauh. Secara praktis, biasanya dilakukan proses muting prosesing data seismik dengan pemodelan medium isotropi sehingga dapat kehilangan informasi – informasi penting khususnya tentang keberadaan litologi. Penelitian ini menggunakan pendekatan anisotropi untuk mreduksi residual moveout untuk data pada ofset jauh pada medium vertical transverse isotropy (VTI). Metode ini menghitung parameter anisotropi model eta, epsilon dan delta dengan menggunakan pendekatan inversi yang dikontrol dengan data sintetik model. Hasil dari penelitian ini menunjukkan bahwa metode waktu tempuh nonhiperbolik  optimized Fomel dan Stovas lebih baik dalam mereduksi residual moveout untuk medium anisotropi dengan ofset jauh yang dibandingkan terhadapa metode waktu tempuh hiperbolik, Alkhalifah, dan Fomel dan Stovas. Selanjutnya, metode optimized Fomel dan Stovas bisa juga mengestimasi litologi reservoir khususnya batuan serpih (shale). Nilai dari parameter anisotropi eta hasil inversi dari persamaannya sendiri mendekati atau sama dengan nilai eta  inisial data sintetik model. Begitu halnya untuk nilai  dan delta  memiliki nilai yang sama dengan inisial model sintetik data khususnya untuk litologi batu serpih (shale). Metode optimized Fomel dan Stovas bisa digunakan untuk mengindikasikan parameter litologi khususnya batu serpih (shale).

 

 

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Seismic anisotropy is expressed as the velocity of seismic depending on angle. Knowledge of anisotropy is essential for seismic data. The anisotropy phenomenon is due to the variation of dep layer, and it is due to the further seismic wave propagation at far offset. Normal moveout (NMO) correction using hyperbolic method has not been maximized and still shows the hockey stick phenomenon at far offset. Practically, mutting process is done, so that it will lose many informations, such as lithology. This research using anisotropic approach to reduce residual error for vertical transverse isotropy (VTI) media at far offset. This method calculated  anisotropy parameters eta , epsilon , delta  using inversion method which is controled synthetic data model. The result showed that the optimized Fomel and Stovas is better in reducing residual at far offset than hyperbolic, Alkhalifah, and Fomel and Stovas. Furthermore, optimized Fomel and Stovas is used to estimate anisotropy parameters for reservoir lithology, especially for shale. The inverted anisotrpy parameter  value is approaching to initial model value. The value of epsilon  and delta parameters also approaches to initial model value.  The optimized Fomel and Stovas method could indicate the anisotropy parameter of reservoir lithology, especially for shale.

 

Abstrak :
ABSTRAK
Pemberian jaminan pengiriman data dengan melakukan implementasi mekanisme error recovery untuk sebuah lingkungan multicast adalah suatu implementasi yang sulit, terutama untuk jaringan multicast berskala besar. Pendekatan paint to point recovery seperti pada TCP tidak dapat memberikan hasil yang baik untuk sebuah lingkungan multicast karena menimbulkan beberapa masalah. Secara umum masalah-masalah pada mekanisme error recovery pada multicast dapat diklasifikasikan menjadi tiga yaitu ledakan paket kontrol ACK/NACK (implosion), timbulnya duplikasi retransmisi paket ketika terjadi loss (duplikasi reply), dan terakhir adalah besarnya cakupan wilayah recovery yang dinilai berdasarkan tingkat exposure dan nuisance. Exposure adalah perbandingan antara jumlah receiver yang menerima paket reply dengan jumlah receiver yang membutuhkan paket tersebut, sedangkan nuisance didefinisikan sebagai perbandingan jumlah paket reply yang didapatkan oleh sebuah receiver akibat loss yang terjadi di suatu tempat dengan jumlah total loss yang terjadi.

Dalam tulisan ini akan dikemukakan sebuah konsep mekanisme error recovery ?Optimized Local Repair" dan penerapannya dalam suatu lingkungan multicast. Pada tulisan ini juga akan diperlihatkan bagaimana mekanisme ini mengatasi dua masalah pertama. Sedangkan untuk masalah ketiga, dilakukan simulasi pada topologi binary tree untuk mendapatkan hasil numerik performansi mekanisme terhadap exposure dan nuisance.

Dari hasil simulasi, didapatkan hasil yang menunjukkan bahwa mekanisme ini mampu mengatasi masalah exposure dan nuisance dengan baik. Penambahan jumlah receiver tidak mempengaruhi kemampuan mekanisme ini, bahkan nilai nuisance akan semakin kecil sejalan dengan pertambahan receiver.

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Abstrak :
Rice husk is one of the most abundant biomass wastes in Indonesia. One way to convert it into an alternative source of energy is biomass gasification. This is a thermochemical process which converts biomass feedstock into fuel gas or chemical feedstock gas (producer gas). The gasification type which is developed in this study is fixed bed downdraft type due to its low tar content and compatibility in microscale implementation. One major problem with the implemented biomass gasification reactor was ruggedness of the partial oxidation process due to the absence of air in the reactor?s middle section, which consequently affected the pyrolysis zone. Several experiments were conducted previously using coconut shells and rice husks as solid feedstock, where an equivalence ratio (ER) of 0.4 was obtained. Therefore, in order to optimize the pyrolysis zone, the modification conducted involves adding a circular air intake into the gasifier. Experiments were conducted in a pyrolysis temperature range of 300?700oC with ER variation of 0.19, 0.24, 0.27 and 0.31. The results show that a good quality producer gas is produced at an ER value of 0.24. This value shows a promising result because the ER value of biomass gasification standard is 0.25.

Abstrak :
Rice husk is one of the most abundant biomass wastes in Indonesia. One way to convert it into an alternative source of energy is biomass gasification. This is a thermochemical process which converts biomass feedstock into fuel gas or chemical feedstock gas (producer gas). The gasification type which is developed in this study is fixed bed downdraft type due to its low tar content and compatibility in microscale implementation. One major problem with the implemented biomass gasification reactor was ruggedness of the partial oxidation process due to the absence of air in the reactor’s middle section, which consequently affected the pyrolysis zone. Several experiments were conducted previously using coconut shells and rice husks as solid feedstock, where an equivalence ratio (ER) of 0.4 was obtained. Therefore, in order to optimize the pyrolysis zone, the modification conducted involves adding a circular air intake into the gasifier. Experiments were conducted in a pyrolysis temperature range of 300–700oC with ER variation of 0.19, 0.24, 0.27 and 0.31. The results show that a good quality producer gas is produced at an ER value of 0.24. This value shows a promising result because the ER value of biomass gasification standard is 0.25.

Abstrak :
Bromat terbentuk ketika air yang mengandung bromida diozonisasi seperti pada proses pembuatan air minum dalam kemasan (AMDK). Bromat merupakan senyawa hasil samping anorganik yang keberadaannya dalam air minum harus diperhatikan karena sifatnya yang berpotensi karsinogen. Penelitian ini bertujuan mendapatkan metode yang sensitif, selektif, dan valid untuk analisis bromat dalam AMDK menggunakan KCKT secara derivatisasi pra kolom dengan elusi isokratik. Fase gerak yang digunakan metanol-air (65:35) dengan laju alir 1 mL/menit. Bromat yang ditambahkan bromida dengan jumlah berlebih dalam suasana asam dapat membentuk bromin. Bromin yang terbentuk segera bereaksi dengan asetanilida menjadi 4-Bromoasetanilida yang dapat terdeteksi pada panjang gelombang 250 nm. Kondisi analisis yang telah dioptimasi kemudian divalidasi mencakup akurasi, presisi, linieritas, selektivitas, batas deteksi (LOD), dan batas kuantitasi (LOQ). Metode ini tidak membutuhkan penanganan sampel yang khusus sehingga lebih cepat dan efisien dibandingkan metode derivatisasi lainnya. Batas deteksi (LOD) metode ini pada konsentrasi 2,61 ng/mL serta dapat menetapkan kadar bromat di atas konsentrasi 8,70 ng/mL. ...... Bromate is formed when water containing bromide is ozonated in production of drinking water. Bromate is the most important inorganic disinfection by-product whose concentration in water should be controlled because of its carcinogenic properties. This study aimed to obtain a sensitive, selective, and valid method for analyzing bromate in drinking water that was performed by using HPLC with pre-column derivatization and isocratic elution. Mobile phase was methanol-water (65:35) with flow rate of 1 mL/minute. Bromate was mixed with excess bromide in acid medium to form bromine. Bromine, which is formed, will immediately reacts with acetanilide and was converted to 4-Bromoacetanilide that detectable at wavelength of 250 nm. Optimized analytical conditions were further validated in terms of accuracy, precision, linearity, selectivity, limit of detection (LOD), and limit of quantitation (LOQ). This method did not need a special sample treatment so that was faster and more efficient than others derivatization methods. The limit of detection (LOD) was at the level 2,61 ng/mL and was successfully applied to assay bromate at the concentration above 8,70 ng/mL.

Abstrak :
The book shows how simulations long history and close ties to industry since the third industrial revolution have led to its growing importance in Industry 4.0. The book emphasises the role of simulation in the new industrial revolution, and its application as a key aspect of making Industry 4.0 a reality and thus achieving the complete digitisation of manufacturing and business. It presents various perspectives on simulation and demonstrates its applications, from augmented or virtual reality to process engineering, and from quantum computing to intelligent management. Simulation for Industry 4.0 is a guide and milestone for the simulation community, as well as those readers working to achieve the goals of Industry 4.0. The connections between simulation and Industry 4.0 drawn here will be of interest not only to beginners, but also to practitioners and researchers as a point of departure in the subject, and as a guide for new lines of study.

Abstrak :
This book provides a solid background for understanding the immediate past, the ongoing present, and the emerging trends of additive manufacturing, with an emphasis on innovations and advances in its use for a wide spectrum of manufacturing applications. It contains contributions from leading authors in the field, who view the research and development progress of additive manufacturing techniques from the unique angle of developing high-performance composites and other complex material parts. It is a valuable reference book for scientists, engineers, and entrepreneurs who are seeking technologically novel and economically viable innovations for high-performance materials and critical applications. It can also benefit graduate students and post-graduate fellows majoring in mechanical, manufacturing, and material sciences, as well as biomedical engineering.