Malam Kekal

Malam tak pandai mengekang
Birahi segan pudar lekang
Dingin terkutuk butuh teman

Aku nyerah pejamkan mata
Besok kerja ini lanjut itu
Sepi malam bertambah liar

Aku hujamkan bertubi-tubi
Bulan keparat senyum bisumu
Aku puas lekas binasa

Sepi malam penuh muslihat
Mau tak mau kubenci siang
Karena malam selalu kekal

LaCoste Gravimeter

LaCoste gravimeter is a portable instrument used to measure gravitational acceleration. It is used in oil and gas exploration. A schematic diagram of the LaCoste gravimeter is shown above. Its components are relatively simple: a rod of length l, a spherical test mass of mass m, and a spring with a spring constant k.

The gravitational acceleration is measured by the slight rotation of the rod. The entire assembly must be calibrated when in static equilibrium. For this reason, it is a relative gravitational measurement system.

One can perform a dynamics analysis to find the equations that relate the rod deflection to the gravitational acceleration felt by the test mass and to the amount of stretch the spring experiences. This can be done simply by assuming a massless rod, a massless spring, and no relative motion at the contact point C between the rod and a support mechanism attached to the vertical wall.

A more detailed - thus realistic - analysis, however requires that one pay attention to

1. Relative motion at the contact point C. This will contribute to the energy dissipation by the torque and the sliding at the contact point.

2. The mass of the spring. As the spring deforms, its centre of mass changes and thus has its own kinetic energy.

3. The mass of the rod. As the rod rotates, it has its own kinetic energy and potential energy.

Such detailed analysis will prove complicated using Newton's laws of motion since the considerations for the energy conservation and mechanical forces acting on the system become separate. One needs also to pay attention to the angular momentum of the sytem. A better way is to use Lagrangian mechanics.

Nasi Liwet Bu Wongso Lemu

Sejak kecil, saat liburan Hari Raya di kota Solo, saya pasti diajak makan nasi liwet Bu Wongso Lemu di jalan Keprabon, tidak jauh dari kraton Mangkunegaran. Warungnya sederhana sekali dan terletak di pinggir jalan. Kita duduk lesehan di malam hari. Ditemani temaram lampu minyak.

Bapak saya cerita Bu Wongso ini punya prinsip berjualan yang tidak memaksa dirinya melebihi batas yang dia rasakan. Jika jualan sudah habis, ya warung Bu Wongso ini tutup. Tutup lebih awal tak masalah walaupun yang antri beli nasi liwet berjejer panjang. Bu Wongso seakan tidak peduli. Dia tetap memasak sebanyak yang dia rasakan sebagai batas maksimum. Kiat bisnis ini dijalankan juga oleh Warung Sate Buntel Mbok Galak di utara kota Solo, yang cukup sering tutup sore jika sudah habis.

Entah mengapa cerita ini membekas di hati saya. Sampai sekarang. Kalau dipikir lagi, saya ingat terus cerita ini karena jadi pengingat untuk tidak rakus. Bahwa hidup ini harus seimbang. Bahwa hidup itu harus berprinsip.

Cerita Nasi Liwet Bu Wongso Lemu muncul di benak saya saat membaca banjir besar Jakarta 2 hari lalu. Jakarta ini seperti warung nasi Bu Wongso yang sangat laris. Semua orang antri untuk tinggal di Jakarta. Semua orang ingin berinvestasi di Jakarta. Membangun jalan tol, mall, restoran, warung, sekolah, gedung bertingkat untuk mencari uang.

Jakarta – lewat pemerintahnya – tapi tidak bertindak seperti Bu Wongso. Karena lupa diri dan kesempatan cari untung sendiri, Jakarta mengangguk terus saat melihat yang antri panjang sekali. Wah, gue bisa untung besar nih, gumam Jakarta. Dan yang dibilang pembangunan berjalan tanpa berhenti.

Yang dibilang pembangunan ini ternyata pengrusakan. Lingkungan alam Jakarta rusak parah. Kenyamanan hidup diganti racun asap knalpot, kebisingan dimana-mana, dan kemacetan tanpa henti. Pusat pemerintahan: oke. Pusat bisnis: oke. Pusat hiburan: oke. Pusat pendidikan: oke. Semua dicaplok dan tidak ditakar. Rakusnya Jakarta akhirnya merusak dirinya sendiri. Banjir menyapa tiap tahun dan semua warga Jakarta sengsara. 

Rakus yang luar biasa ini terjadi karena tidak ada yang mengerem. Semua pihak yang mencari untung berpusat di Jakarta dan mudah berkomplot untuk menambah untungnya sendiri. Jika ingin perkasa, tinggal lah di Jakarta. Komplotan-komplotan ini berdekatan satu sama lain. Mencari uang tidak pernah berhenti karena jika berhenti sebentar, tetangga sebelah bisa lebih kaya dari kita.

Tidak tahu batas juga menjadi alasan kenapa rakus bisa merajalela. Orang tidak tahu batas jika dia tidak mau bersikap obyektif: mendengarkan usulan orang lain, mengenal diri sendiri, menambah wawasan. Jakarta tidak beda seperti orang yang tidak bersikap obyektif. Semua mau dicaplok. Tidak seperti Bu Wongso yang paham keterbatasan dirinya sendiri.

Oil & Gas Survey Data as Conditional Probabilities

I was faced with an interesting question over the weekend when my industrial colleagues asked me how to summarize and present oil and gas survey data as a function of whether these data lead to drilling that produced reservoirs with commercial success. These data are critical for both oil and gas (exploration and production) companies and survey companies that provide survey services to the E&P companies.

The data set that my colleagues want is the probability of correctly detecting the commercial reservoirs using the survey data. Being able to state the success rate of identifying commercial reservoirs using a certain survey method is valuable and important to potential clients. The data that they have is the success rate of the drilling campaigns based on the survey final recommendations. These two sets of data are of course related, but they are not the same.

One tricky aspect of solving this problem is that the oil and gas companies that employ different survey methods do not want to reveal their drilling success rate for either practical or confidentiality reasons. In other words, the success rate of identifying commercial reservoirs using a particular survey method – be it seismic, electromagnetic, or gravitational – has to be determined from incomplete data.

These incomplete data do not necessarily lead to complications. There are ways to go around them using probability formulas. In fact, the final formula–as it turns out–allows me to obtain the success rate of identifying commercial reservoirs using only data that depend on other factors, i.e., using only "conditional probability" data.

One interesting result I found, for example, is the success rate of identifying commercial reservoirs depends on the success rate of a survey method to correctly identifying both commercial reservoirs and non-commercial reservoirs. Correctly identifying commercial reservoirs alone does not give a full picture on how good a survey method is. We should also need to know how good the survey method in correctly identifying non-commercial reservoirs as well.

The conditional probability formulas I use to summarize and present the oil and gas survey data can also be used to validate a claim by an oil and gas survey company. This validation process is important for an oil and gas company to decide which survey company it should hire to maintain or increase its production target.

Pancasila Hidup dan Lestari

1. Ketuhanan Uang Maha Esa.

2. Kemanusiaan Uang Pandir dan Biadab.

3. Persatuan Uang Indonesia.

4. Kerakyatan Uang Dipimpin oleh Nikmat Kebiadaban, Dalam Permusyahwatan dan Percakilan.

5. Keadilan Uang bagi Seluruh Rakyat Indonesia.

Global Citizen

I was accidentally born in Indonesia. Each of us was born with predetermined conditions, including nationality, we could never choose or refuse.

If the place we grew up in proves nurturing, we grew to love it. I love Surabaya mostly for its people. Surabayans are egalitarian in a country still reeks of feudalism, loud, prone to swear expletives, and say exactly what is in their mind. We are the rude Javanese, as most Indonesians would say.

This love of land is exploited in patriotic propaganda by a government and its apparatus that want loyalty and obedience from its citizens. The government would go even further by using our love of food, football club–or whatever else–and even religion to appeal to our patriotic zeal.

But we know better. Since the food was never created by such government. Only a few determined creative citizens created them, mostly out of love in what they do. The football club is in it for the money and does not care about any propaganda that does not make one. And even the religion is imported from a faraway land. So, what is claimed as ours–ours alone–is nothing but an illusion since it is never mine in the first place.

I feel even more stupid if I believe in such propaganda by claiming that Surabayan food is the best in the world. Because it never is. Since I actually like Indian breakfast of paratha, sambar, and chole, Vietnamese pho, Canadian beer, and Alberta beef steak. I grow to love other places and people too.

I have grown to be a global citizen. I can imagine living and dying in another place other than Indonesia. This was how I felt when my family and I left Indonesia last year after working there for 1 year to return to Canada. 

The place I grew up in does not have the same feeling as I felt when I was a kid. Java is now dotted with cities choked in traffic jams, floods, and overpopulation. Its government is corrupt and very slow to improve the welfare and health of its people. Its elite and rich is crass and ostentatious.

I was heartbroken but felt incapable of making enough changes. Maybe next time, I said to myself, when my kids are grown up. You see, first love is hard to erase. But at least this time, I am the one who will choose.