Gemilang Astro Blog

Kajian Singkat Riser Interference

2012-02-14T05:30:00.000+07:00

Oleh : Gilang Muhammad Gemilang

1.Pembukaan

àKetika eksplorasi minyak dan gas terus bergerak ke kondisi perairan yang lebih dalam, metodologi yang akurat untuk menaksir terjadinya gangguan riser menjadi semakin penting. Hal ini disebabkan, karena risiko interferensi antara riser meningkat ketika riser yang digunakan dalam ukuran sangat panjang sesuai dengan kedalaman laut.

à Kajian singkat ini akan mengangkat persoalan bagaimana prosedur yang tepat untuk menaksir analisis kelayakan dan desain praktek dengan fokus sehingga antara riser tidak terjadi tabrakan.

àistilah “Riser” dalam Kajian ini bukan hanya berarti riser saja, melainkan juga seluruh sistem dalam riser diantaranya ialah umbilical, flexible riser, Steel Catenary Risers SCR dan Top Tensioned Risers (TTRs).

2.Pendekatan Desain

Pada umumnya riser didesain sedemikian rupa sehingga sanggup manahan beban beban lingkungan seperti gerakan struktur terapung, gelombang, arus, angin dan lain lain.

Banyak hal yang menjadi faktor desain risers, diantaranya ialah:

àbeban lingkungan

àKedalaman laut

àKonfugurasi riser

àPertumbuhan laut (marine growth)

àInteraksi hidrodinamik seperti VIV(vortex Induced Vibration), wake instabilities, dll

àDan lain lain

Perbandingan antara berat/diameter dari suatu pipa riser selalu dijadikan acuan agar dapat menghasilkan sifat yang sama dengan kasus sebelumnya . Namun perlu dicatat, bahwa perbadingan berat/ diameter sangat dipengaruhi oleh pertumbuhan laut (marine growth) yang artinya berkaitan dengan umur struktur. Oleh karena itu, perbandingan rasio / diameter harus selalu diperiksa.

Dalam prinsip desain, terdapat dua jenis strategi desain pada riser di laut dalam, yakni:

1.No Collisions Allowed

2.Collision Allowed

dua jenis strategi desain ini memiliki syarat yang berbeda dari segi analisis beban dan beberapa kriteria lainnya. Gaya interaksi antar risers akan dibahas dalam kasus Collision allowed, walaupun kasus No Collision Allowed lebih membutuhkan biaya yang lebih besar dalam kondisi badai.

2.1 No Collision Allowed

Jarak minimum antar riser yang berdekatan harus diperhitungkan sedemikian rupa khususnya pada kasus beban kritis.

2.2 Collision Allowed

Tabrakan antar riser mungkin saja diperbolehkan asal dengan beberapa syarat yang konsekuesinya dapat diterima. Setiap jenis beban juga harus diklasifikasikan menurut probabilitas kejadiannya. Tabrakan ini hanya diperbolehkan dalam kondisi extreme yang sementara atau tak terduga-duga, sedangkan tabrakan dalam periode waktu lama pada umumnya tidak diperbolehkan.

Analisis efek beban statis perlu dilakukan untuk penaksiran kemungkinan terjadinya tabrakan.

Jarak antar riser adalah faktor desain terpenting untuk mencegah tabrakan namun untuk membuat jarak antar riser semakin jauh maka dibutuhkan biaya yang semakin tinggi. Oleh karena itu, dibutuhkan desain yang tepat dan efisien untuk menaksir jarak yang efektif.

Beberapa usaha untuk memperkecil kemungkinan tabrakan antar riser adalah sebagai berikut:

Mengelompokkan riser dengan seukurannya, membersihkan riser dari marine growth, memberikan bumpers untuk memperkecil dampak tubrukan.

3.Interaksi Hidrodinamik

3.1 Umum

Penaksiran interaksi hidrodinamik adalah isu umum untuk efek beban yang berhubungan dengan evaluasi riser interference. Mekanisme beban sgt bergantung pada bilangan reynold sesuai dengan level turbulensi dari aliran fluida yang datang.

Interaksi hidrodinamik pada upstream dapat diabaikan sehingga yang perlu ditinjau hanya downstream. Seperti dikatakan sebelumnya, mekanika beban fisik pada sepasang riser yang berdekatan itu sangat kompleks.

Efek terpenting yang berhubungan dengan penaksiran ini ialah:

— reduced mean forces on downstream risers due to shielding effects tending to bring the risers closer

— VIV effects on mean forces on upstream and downstream riser in terms of drag magnification.

Beberapa gaya non-linear yang bekerja pada upstream riser bisa menambah kemungkinan efek interaksi hidrodinamik sebagai berikut:

— wake instability motions of downstream riser

— multiple static equilibrium positions of downstream riser.

3.2 Gaya mean pada arus steady

Beban hidrodinamik pada downstream riser akan dipengaruhi oleh daerah bangun yang dibuat dari upstream

Eke pada gaya mean di downstream ialah

— reduced mean drag force due to shielding effects

— lift force due to the velocity gradients in the wake field.

Koefisien mean drag dan list akan tergantung pada jarak relatif antar riser, lihat gambar 3-1.

Vo dodefinisikan sebagai arus bebas dengan kecepatan pada upstream riser.

Contoh koefisien mean drag dan gaya lift pada silinder pada daerah bangun di silinder yang lain dengan diameter yang sama ditunjukkan pada gambar 3-2 dan 3-3 sebagai fungsi jarak relatif antar silinder.

3.3 Faktor amplifikasi gaya drag

Gaya drag pada umumnya mengalami amplifikasi yang mengacu pada amplitudo VIV sebagai berikut

Sebagai perkiraan konservatif, nilai sedikit pada sisi tinggi adalah direkomendasikan untuk riser hulu. Untuk riser hilir, adalah konservatif untuk menerapkan nilai batas bawah untuk drag karena viv amplifikasi. Hal ini akan cenderung untuk membawa berarti

posisi anak tangga lebih dekat satu sama lain. Jadi, terpisah Viv penilaian untuk hulu dan hilir- riser diperlukan sebelum gangguan riser global yang analisis. Sebuah alat negara-of-praktek penilaian Viv harus diterapkan, lihat misalnya / 23 / atau / 26 /. Riser hulu konservatif harus diperlakukan sebagai riser terisolasi. Para viv tanggapan atas riser hilir secara umum harus didasarkan pada lokal masuk kecepatan pada posisi wakil berarti menjadi bagi Viv respon. Perhatikan bahwa informasi yang sangat terbatas tersedia tentang Viv perilaku dari riser yang terletak di bangun dari satu hulu. Sebuah respon konservatif batas bawah Viv oleh karenanya harus diterapkan untuk riser hilir. Hal ini dianjurkan untuk tidak menggunakan VIV pada riser hilir sebagai perkiraan pertama.

4.Penaksiran Clearance Riser

Kriteria jarak minimum dapat dilihat di gambar 4-1

Dengan latar belakang ini, dengan jarak bebas minimal dua kali diameter luar yang direkomendasikan untuk anak tangga dengan luar sama diameter. Jumlah dari diameter luar yang direkomendasikan sebagai penerimaan kriteria dalam hal diameter luar yang berbeda. Oleh karena itu, untuk menghindari tabrakan jarak minimal diberikan oleh ∆ ≥ D1+D2

Kriteria ini tidak mencerminkan faktor keamanan.

Protection of Indigenous

2011-10-16T08:49:00.002+07:00

Protection of indigenous, ancient, and traditional knowledge Statement of the Problem For almost a decade, Goverment have been struggling with the issue of the protection of traditional knowledge (TK). Based on pasal 29 RUU Paten –Renewal Condition in my Country (Indonesia).

The Inventor is obligated to provide Disclosure of origin and Evidence of Prior Informed Consent in the Process Registration of Patent. Inventor who use Sources of Traditional Knowledge regarding gene property need to put footnote from where invention be advocated with proven consent of right People who is in charge of that Traditional Knowledge.

This Obligation has always been said in Government Regulation Patent Of Developing country such as Indonesia who is specified as Mega diverse. Beside That, the obligation rule has a significant meaning of strategic in UU Patent Indonesia. A common Solution of Biopiracy is based on Traditional Knowledge, generally the obligation of disclosure of origin dan evidence of prior informed consent is really needed and help examiner to judge renewal Condition, inventive step and make invention implemented efficiently.

Nevertheless, this obligation caused a bad impact if it used to oppose giving patent Right from Traditional Knowledge without Noticing and examining Patent Rigth Conditions. Those Policy potentially be assumed defying the consistences of TRIPS Covenant. To prevent fot that, policy of disclosure of origin dan evidence of prior informed consent need to be ruled as follows.

a. Obligation is Conducted during substantive Examination;

b. Obligation is part of Condition renewal;

c. Obligation need to be provided with Document or database categorazied as non-literature patent.

Government hasn’t stated promptly policy regarding source natural gene, Renewal Condition is one of strategic condition to impose whether Invention could be approved or not. Based On many case that occurred in United states or United Kingdom, leaked invention regarding with traditional Knowledge and source Natural Gene is Because the Traditional Knowledge and natural source Gene has not become Prior Art in law of Patent System. Therefore Pasal 3 Rule as Follows: Invention could be approved if the Approval time is not same as prior technology.

Secondly, I want to explain my personal view to this topic. There have been various attempts in communities around the world to try and secure their TK from being exploited and biopirated by others. They should make a patent to the invention to prevent from biopirated. But the patent should not make people which use the traditional knowledge be in troublesome caused by Biocapitalism. Therefore, it needs rule to make all parties gain profit. As a result, the measures implemented should be seen as stepping stones and events to learn from in working towards a more unified, strengthened, international system for TK IP protection, not as stand-alone solutions in and of themselves.
Thirdly, I have an Idea to be solution to the problem we face, every TK and IP is secured by Registered in Secured Patent List by government. So Government gather all data that have been TK and IP in all over the Country. Every inventor that want to make Patent need to be examined and checked with all TK and IP reserved. Government needs to be more concern about how creativity grown in the country by making transparency policy and advertising good propaganda to make people more eager to synchronize TK, IP and Technology reserved nowadays.

Global Finance Storm

2011-07-13T19:41:00.000+07:00

Global Finance

Global Finance is a wide topic to be discussed. it involves people all over the world who stand their life with money. The global financial system (GFS) is the financial system consisting of instituion and regulators that act on the international level, as opposed to those that act on a national or regional level. The goal of Global Finance System is to allow markets to exchange information and financially impact each.

Global Finance system is controlled by economic activities in each country all over the world. there are many organizations contributing in Financial System. in international, they have IMF and World Bank. in regional, we have ASEAN and ACFTA as our trading beraucracy and in national level we have the ministry of finance and BI.

Nowaday, Global Finance system face crisis called GFC (Global Finance Crisis). The global financial crisis, brewing for a while, really started to show its effects in the middle of 2007 and into 2008. Around the world, stock markets have fallen, large financial institutions have collapsed or been bought out, and governments in even the wealthiest nations have had to come up with rescue packages to bail out their financial systems.
The main Player of Global finance are :

1. Global

• IMF à to build a framework for economic cooperation and ensure that the international monetary system remains stables

• World Bank à to provide funding, take up credit risk or offer favourable terms to development projects mostly in developing countries that couldn't be obtained by the private sector

2. National

• Government

• Ministry of Finance

• Bank Indonesia

3. Regional

• ACFTA

• ASEAN

This article provides an overview of the crisis.
The financial Crisis is related to economic condition in the US, as indonesia rely it's economic system on US. many of our economics system are adopted from US. Basically, the problem started from the US government that empower the people to do some alternative of bussiness in property.

especially in making home, no longer live in apartment which is more conservative to save more plain area. Because of that policy, many national and private banks in the US give an easy loan to the people without analysing the financial qualification of the people who wants to start the property business. the easy loan also means the low rate of investment which in range between 0,25% - 1% whereas the normal value is about 3-5%. those are the external factors. there is also internal factors which has occured many times before. That is the tendency of the US citizen to deposit their money rather than to spend it.

when they want to start the property bussines, they did it with credit without cash. Therefore, in simple way we can that there were a condition where it was lack of cashmoney. Therefore, no money circulation in the country. These aspects lead them to an unstabel economic situation and unstable economics, many industries being "ruined", and then the industrial demand were decreasing. The US industrial demand including: minerals, oil, agriculture products, textile, food, etc.

Now, how it affects indonesian economic situation? the explanation starts from the main economic activity in Indonesia which is the household spend. This spend usually depends on the rate of their husband's salary. so, the salary rate is depends on the performance of the economic activity, the major acitivity is exporting our products, while export activity depends on the natural resources.

as we majorly export the "raw material" of nature rather than to process it first, demand of the other countries remain still that being the destination of our export products.that is the flow of the economic activity in Indonesia,while the demand (from the US, as the indonesian products majorly exported there) decreasing,

then it affected the performance of the manufacturer in indonesia

while the demand decreasing --> the performance of exporting decrease --> the salary decrease, --> the main activity (which is household spending) also being "ruined”. beside that, because of the lack diversity in the products, and the countries we export our product to, it also affects the export performance. lack of diversity in products means indonesia was only rely on their export to several products like natural resources, textile, and food. nothing more.

lack of countries means we were only export our products to several big countries, majorly US, and europe. also japan, and china in asia region. so when the US demand decrease, then it is logic that indonesian economical activity would be affected as well. but however, the economic analyst said that indonesia has done a great job struggling in the crisis.

Therefore, the crisis affected not that bad to indonesian economy. it is because the production of indonesian manufacturer are being took over to be delivered to the domestic need. in simple way, indonesian still has it's market, but now it is in domestic market. the principal is just to balance the demand (whereever it from) and the supply (from the manufacturer)so, the last statement is the end of the analysis, which is the policy proposed by the economy analyst. they proposed two alternatives, which are the improvement in macroeconomic and microeconomics.

from macroeconomics, it is the monetary system. means that government has to control the circulation of cash money in this country. then the microeconomics: its more to the improvement of investation

so it is about the regulation of our bank that gives the people all the ease to start investing and also improvement in the production and manufacturing system in this country UKM and many national company is the alternative to avoid the global decreasing demand. in the simple way, the products in indonesia are produced by us, and consumed also by us. (although it is not as simple as it heard).

While microeconomics is all about the technical thing, rather than a governmental policy thing. and as an engineer we need to criticize this problem delicately.

Terbaik dan Terindah-ku

2008-12-09T19:36:00.000+07:00

Saat orang-orang TIMUR berkata

BULAN itu Indah

...Aku Diam...

Saat orang-orang BARAT berkata
BINTANG itu Indah
...Aku Diam...

Saat orang-orang UTARA berkata
AURORA itu Indah
...Aku Diam...

Saat orang-orang SELATAN berkata
PELANGI itu Indah
...Aku Diam...

Saat orang-orang Terdiam

...Aku Berkata...

..._____...lah yang paling INDAH

isi

nama yang paling indah disini

dan sejujurnya yang paling indah
menurutku diantara semua ciptaan Allah SWT ialah ..._____...

(I knew before I know)

hmmmm....................... Terima kasih Ya Allah

(karna telah menciptakannya)

Namun Yang Menjadi Pertanyaan Besarku Sekarang ialah

Apa Aku Bisa Menuntun kmu ke Syurga???

Apa aku pantas menjadi IMAM-mu???