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"Pendahuluan : Kegiatan usaha Minyak dan Gas Bumi, dari hulu sampai hilir mempunyai peranan dalam memberikan nilai tambah bagi pertumbuhan ekonomi nasional secara berkelanjutan. Salah satu peralatan operasi paling panting dalam kegiatan usaha Minyak dan Gas Bumi adalah tangki penimbun. Hasil produksi usaha Minyak dan Gas Bumi, balk sebelum dan sesudah proses pemumian pengolahan, disimpan di dalam tangki penimbun. Dalam operasinya, tangki penimbun dapat mengalami kegagalan operasi seperti kebocoran, kebakaran, tumpahan, ledakan, collapse yang disebabkan oleh vacuum dan menggelembung bahkan pecah yang disebabkan oleh overpressure. Berdasarkan hal -hal tersebut di etas, maka perlu dilakukan analisis lebih lanjut unluk mengetahui kemungkinan adanya faktor lain yang menyebabkan collapsenya tangki A-24.Metode: Penelitian ini menggunakan pendakatan metode analisis pohon kegagalan (Fault Tree Analisys) untuk mengetahui faktor-faktor yang berpengaruh terhadap kejadian colLapsenya tangki A-24, dengan melakukan studi evaluasi kualitatif dan semi kuantitatlf dimana data yang diteliti berasal dari data primer (laporan hasil penyelidikan) dan data sekunder yang terkait dengan kebijakan perusahaan, peranoangan, pengoperasian, inspeksi dan pemeliharaan tangki penimbun dan peralatan lain yang ada di PT. X. Diharapkan dengan analisis pohon kegagalan ini diketahui faktor atau beberapa faktor yang paling dominan penyebab collapsenya tangki A-24.Telitian: Aspek input adalah kebijakan perusahaan mengenai K3LL, dokumen desain dan konstruksi tangki, pompa dan peralatan lainnya, Dokumen operasi, inspeksi dan perawatan tangki termasuk peralatan pemafasan tangki, pompa dan peralatan lainnya serta laporan kecelakaan Collapsemya tangki A-24. Aspek Proses adalah evaluasi kebijakan perusahaan, pengumpulan data, evaluasi dan analise data menggunakan Fault Tree Analysis. Aspek output adalah diketahuinya penyebab paling dominan collapsenya tangki A-24 den adanya rekomendasi untuk mencegah terjadinya collapse dimasa yang akan datang.Kesimpulan : Faktor yang mengawali terjadinya penyebab langsung dan penyebab dasar adalah kelemahan kontrol atau pengawasan oleh manajemen. Faktor paling domlnan penyebab collapsenya tangki A-24 disebabkan tidak berfungslnya breather valve dan goose neck (unsafe condffion). Faktor - faktor seperti operasi pampa tidak normal, korosi atap dan dinding tangki, perubahan cairan yang ditimbun dan perubahan temperatur atau tekanan cairan di dalam tangki dapat secara tidek langsung menyebabkan collapsenya tangki A-24 (unsafe condition). Sedangkan belum sempurnanya instruksi tertulis, kurangnya kepatuhan tehadap perundang-undangan serta kurangnya pengetahuan dan kelerampilan SOM secara tidak langsung menyebabkan collapsenya tangki A-24 (basic cause dan lack of control).

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Oil and gas operation activities, from the downstream to the upstream, have a great role in giving some add values to the continuous growth of the national economics. One of the most important equipment in the oil and gas operation activities is the storage tanks. Oil and gas products, before and after the refinery processes, are stored in the storage tank. In its operation, storage tank may undergo some operation failures, such as leakage, fire, spill, explosion, collapsed (caused by vacuum condition) and even burst (caused by overpressure). Based on the situation above mentioned, it is important to make a further analysis to find other possible factors that cause the A-24 tank to collapse.Method: This research use Fault Tree Analysis method to find factors that are affecting A-24 tank to collapse, using qualitative and semi-quantitative study to evaluate primary data (investigation report) and secondary data related to company policy, design, operation, inspection and maintenance of the storage tank and other equipment in PT X. From this fault tree analysis, it is expected that the most dominant factor or factors to the collapse of the A-24 tank can be found.Concern: The input aspects are company policy on safety, health and environmental; tank, pump and other equipment design and construction documents; operation, inspection and maintenance documents of tank and its breathing equipment, pump and other equipment; and incidental data of the A-24 tank collapse case. The process aspects are company policy evaluation and data collection, evaluation and analysis using Fault Tree Analysis method. The output aspects are to find the most dominant cause of the A-24 tank collapse and to give recommendation to prevent tank collapse in the future.Summary: The factor that starts direct cause and basic cause is management lack of control or supervision. The most dominant factor to the A-24 tank collapse is the malfunction of breather valve and goose neck (unsafe condition). Some factors, such as abnormal pump operation, corroded tank roof and shell, change of liquid stored, and change of liquid temperature and/or pressure inside the tank, may indirectly cause the A-24 to collapse (unsafe condition). While improper written instruction, lack of compliance to regulation, lack of knowledge and unskillful human resources, may indirectly cause the collapse of the A-24 tank."

"ABSTRACTInternal Erosion initiated by water movement along channels called tunnel erosion, oftencrack or defect the dam?s structure. It is one of the main causes of water structure?s (dams,dikes, etc.) collapse. This phenomenon can be divided into 3 phases, tunnelling, collapse, andthe opening of the channel inside the dam [1]:- ?Tunnelling? transport large quantities of particles due to the hydraulic gradient. It?s happenfast in a preferential path especially in some point of dam structure?s weaknesses.- The gradual collapse of the roof of tunnel erosion allows the expansion of the channel.- The opening of the channel is started after the collapse of the channel by tunnel erosion.Research has been done to explain the phenomenon of collapse, but there are still questions,including the formulation, phase, and form of the rupture. Moreover, the equation usedis not always adapted to the various cases of the soil. Research by Hunt and Hanson showedthe different phases of a dam collapse with a rate of expansion of a hole driven only by theconstraint of shearing.Through this numerical study, we find that their hypothesis is not correct, because thereare other parameters that affect this phenomenon and also the effect of traction force. Thestudy is simplified by modelling an earthen dam with a given cavity; where the undrained cohesionis controlled to see at which value of cohesion the fracture achieved. This simplificationis the opposite in the real case, where the cohesion is fixed but the cavity expands. Wefind that the collapse of the earthen dam because of the tunnel erosion occurs in two stages:the arching effect in the channel across the dam that makes vertical sag then collapse, and theexpansion of the channel which is inclined more like a slope. The high of the dam and theform of the ?tunnel? cavity also influenced the failure mode."

"Pada penelitian ini akan dilakukan analisis pada struktur baja dengan sistem concentric braced frameterhadap ketahanannya mengatasi progressive collapse saat terjadinya penghilangan kolom. Metode analisis yang akan digunakan adalah analisis statis linear dan nonlinear dengan maksud untuk mengetahui efektivitas dari kedua metode analisis. Variasi pada jumlah lantai dan lokasi penghilangan kolom dilakukan untuk mengetahui hubungannya dengan proses terjadinya progressive collapse.Model yang digunakan adalah model berdasarkan jurnal acuan dan model berdasarkan hasil desain sesuai dengan SNI 1726:2012. Penggunaan standar desain bangunan gempa dilakukan pada tahap desain untuk menentukan ketahanan struktur bangunan di Indonesia terhadap progressive collapse.  Nilai demand capacity ratio dan overload factorakan digunakan untuk mengetahui dampak terjadinya penghilangan kolom terhadap struktur terhadap kekokohan struktur. Didapatkan bahwa semakin banyak jumlah lantai, semakin kuat struktur terhadap progressive collapse. Struktur berdasarkan hasil desain SNI memberikan struktur yang lebih kuat terhadap progressive collapse. 

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In this study an analysis of steel structures with a concentric braced frame system will be carried out to analyze the resistance to progressive collapse during column removal. The analytical method that will be used is static linear and nonlinear analysis with a view to knowing the effectiveness of the two analysis methods. Variations on the number of floors and locations of column removal were carried out to determine the relationship with the progressive collapse process.

The models used are based on reference journals and based on design results in accordance with SNI 1726: 2012. The use of earthquake building design standards was carried out at the design stage to determine the resistance of building structures in Indonesia to progressive collapse. The value of the demand capacity ratio and overload factor will be used to determine the impact of the removal of columns on the structure against the robustness of the structure. It was found that the higher the structure, the stronger the structure regarding progressive collapse. The structure based on SNI design result provides a structure that is resistance towards progressive collapse."

"Pada tanggal 10 Mei 1990, terjadi peristiwa hebat yang membuatnya menjadi berita utama di sejumlah surat kabar. Peristiwa tersebut yaitu runtuhnya sebuah jembatan di atas Kali Krasak akibat kebakaran truk tangki bahan bakar. Sampai saat ini masih terjadi kesimpangsiuran tentang mengapa dan bagaimana sebenarnya keruntuhan tersebut dapat terjadi. Bahkan terdapat indikasi terjadinya ledakan sebagai awal dalam peristiwa kebakaran itu. Prof. Ir. Sidharta S. Kamarwan, guru besar Teknik Sipil FTUI pada waktu itu, segera memberikan penjelasannya dalam laporan singkat mengenai proses keruntuhan Jembatan Krasak secara analitis. Setelah membaca laporan tersebut, penulis merasa tertantang untuk meneruskan hasil penelitian beliau lebih lanjut, yaitu dengan merekonstruksi peristiwa tersebut melalui simulasi menggunakan program ANSYS V8.0, salah satu program simulasi terbaik berbasis analisa elemen hingga. Simulasi akan dilakukan berdasarkan data-data historis yang diperoleh penulis baik melalui media massa, mewawancarai saksi mata, maupun mengukur langsung dimensi Jembatan Krasak yang masih ada. Perhitungan input beban termal dilakukan berdasarkan literatur dari hasil penelitian terkini. Modelisasi struktur dilakukan secara 3 dimensi dengan model 2 dimensi sebagai pembanding. Analisa struktur dilakukan secara nonlinear, baik material ataupun geometri. Pengamatan hasil dilakukan terhadap perubahan deformasi dan hubungan tegangan-regangan akibat kenaikan suhu. Kedua hal tersebut akan berbicara banyak mengenai urutan kejadian peristiwa keruntuhan Jembatan Krasak yang tidak tercatat dan terlihat oleh media massa maupun saksi mata. Hasil yang diperoleh dari penelitian ini menunjukkan bahwa hipotesa yang dilakukan oleh Prof. Ir. Sidharta S. Kamarwan sudah tepat, yaitu penyebab utama keruntuhan Jembatan Krasak yang berupa kenaikan tegangan elemen akibat kenaikan suhu dan beban tetap ditambah dengan berkurangnya nilai Modulus Elastisitas. Tepatnya kenaikan tegangan tersebut pada simulasi mencapai 1603% dengan penurunan Modulus Elastisitas sebesar 90,7%. Selain itu hasil akhir simulasi mengindikasikan bahwa hal-hal yang dihasilkan oleh simulasi ini, baik langkah-langkah keruntuhan dan hubungan tegangan-regangan tiap batang profil struktur Jembatan Krasak, dapat dianggap sesuai dengan kondisi sebenarnya. Dari hasil simulasi juga didapat bahwa pola keruntuhan yang terjadi pada Model 3D memberikan gambaran yang lebih mendekati kenyataan dibandingkan dengan Model 2D.

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At May 10th 1990, a great incident that making it as almost every newspaper headline happened. That incident was a collapse of a bridge on Krasak River resulting fuel truck tank fire. There are much unclear nesses about why and how exactly the incident happened, even until now. Yet explosion indicated to be happening as the beginning of the incident.

As a Professor of Civil Engineering study, Ir. Sidharta S. Kamarwan soon established his explanation in a short report of analytical study of Krasak Bridge collapse process. After reading the report, came some courageous feeling to continue his research a step forward, with reconstructing the incident through simulation using ANSYS V8.0, one of the best-advanced finite element analysis based engineering simulation programs ever exist.

The simulation will be done based on historical data from reading the news, to interviewing the eyewitness, even with measuring Krasak Bridge's steel profiles dimension itself. Thermal load input calculation was done with formula and charts from the study conducted from the Swedish Method. The bridge's structure will be modeled 3 dimensionally and being compared with its 2 dimensional result. Structural analysis will be conducted with nonlinear analysis, taking into account geometrical and material nonlinearities. Deformation and stress-strain relationship changing caused by temperature rise will be the simulation result that being observed. Those two points could tell us a lot that happened from the sequence of the Krasak Bridge collapse that unseen or unwritten by the eyewitnesses or the mass media.

This simulation result indicated that hypothesis done by Prof. Ir. Sidharta S. Kamarwan was accurate, especially about main cause of Krasak Bridge collapse which was element stress rise resulting temperature rise and constant dead load plus decreasing of Modulus of Elasticity. Those element stress rise that was exactly calculated in the simulation, get higher until 16.03 times bigger than its initial stress. The Modulus of Elasticity itself decreases until 90.7% of its initial value. In the other hand, final simulation result indicates that things obtained by this simulation, from its collapse process to stress-strain relationship of Krasak Bridge structural profile, are appropriate with the original condition. The result also show that the collapse process of 3D model give a better view of what exactly happened at the actual condition rather than the 2D model. "

"Progressive Collapse merupakan penyebaran kegagalan lokal awal dari elemen ke elemen yang mengakibatkan keruntuhan seluruh struktur atau sebagian besar struktur. Pada penelitian ini, dilakukan linear static analysis dan nonlinear static analysis untuk mengetahui potensi terjadinya progressive collapse. Validasi terhadap linear static analysis dilakukan pada bangunan yang ada pada UFC 04-023-03. Studi parametrik dilakukan pada bangunan baja dengan sistem eccentrically braced frame yang diambil dari jurnal dan bangunan yang dirancang berdasarkan SNI 1726:2012. Terdapat tiga macam variasi, yaitu variasi jumlah lantai (4, 8, dan 15 lantai), variasi skenario penghilangan kolom (kolom pinggir dan kolom tengah) dan perbedaan metode analisis. Kesimpulan dari penelitian ini adalah semakin banyak jumlah lantai maka semakin kuat suatu bangunan. Skenario penghilangan kolom pinggir juga akan menghasilkan keadaan yang lebih parah dibandingkan dengan penghilangan kolom tengah. Nilai demand capacity ratio akibat linear static analysis lebih besar dibandingkan dengan nonlinear static analysis.

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Progressive Collapse is the initial spread of local failure from element to element which results in the collapse of all structures or a disproportionately large part of it. In this study, linear static analysis and nonlinear static analysis were performed to determine the potential for progressive collapse. Validation of linear static analysis method was carried out on a building in UFC 04-023-03. Parametric studies are carried out on steel buildings with eccentrically braced frame taken from journal and buildings designed based on SNI 1726: 2012. There are three variations, variation in the number of floors (4, 8, and 15 floors), variation in column removal scenarios (edge columns and middle columns), and variation in analysis methods. The conclusion of this study is the more number of floors, the stronger a building is. The scenario of removing the edge column will also produce a more severe condition than the removal of the middle column. The value of the demand capacity ratio due to linear static analysis is greater than nonlinear static analysis."

"Latar Belakang Kematian ibu dan anak merupakan permasalahan global yang masih dihadapi hingga sangat ini mengingat angka kematian ibu dan anak yang cukup tinggi di Indonesia. Pelatihan merupakan salah satu implementasi metode untuk menekan angka kematian ibu dan anak, keefektifan pelatihan dapat dinilai menggunakan ujian simulasi saat masa pendidikan seorang dokter menggunakan instrument yang sesuai. Metode Penerjemahan Ottawa Crisis Resouce Management Global Rating Scale versi Indonesia dilakukan pada 15 peserta ujian simulasi berdasarkan pengalaman pelatihan. Validasi didapatkan dengan melakukan uji validitas isi dan validitas konstruksi dengan menghitung nilai pearson correlation dan nilai signifikansi. Reliabilitas didapatkan dengan menghitung nilai konsistensi internal dalam bentuk nilai Cronbach Alpha. Hasil Instrumen Ottawa Crisis Resouce Management Global Rating Scale versi Indonesia memiliki rentang nilai korelasi sebesar 0,685 – 0,995 dengan uji KMO Barlett test of sphericity sebesar 0,827 dan nilai reliabilitas Cronbach Alpha sebesar 0,969. Instrumen Daftar Tilik Kasus Maternal Collapse memiliki rentang nilai korelasi sebesar 0,287 – 0,995 dengan hasil dari uji KMO Barlett test of sphericity sebesar 0,668 dan nilai reliabilitas Cronbach Alpha sebesar 0,882, terdapat 2 butir instrument yang tidak valid yaitu Initial Assessment dan Transfer Intensive Theraphy Unit. Kesimpulan Ottawa Crisis Resouce Management Global Rating Scale dan Daftar Tilik Kasus Maternal Collapse valid dan reliable pada kasus Maternal Collapse, namun diperlukan beberapa modifikasi.

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Introduction Maternal and child mortality is a global problem that is still being faced to this day considering that the maternal and child mortality rates are quite high in Indonesia. Training is one of the implementation methods for reducing maternal and child mortality. The effectiveness of training can be assessed using simulation exams during a doctor's training period using appropriate instruments. Method The translation of the Indonesian version of the Ottawa Crisis Resource Management Global Rating Scale was carried out on 15 simulation exam participants based on training experience. Validation is obtained by testing content validity and construct validity by calculating the Pearson correlation value and significance value. Reliability is obtained by calculating the internal consistency value in the form of Cronbach Alpha value. Results The Indonesian version of the Ottawa Crisis Resource Management Global Rating Scale instrument has a correlation value range of 0.685 – 0.995 with the KMO Barlett test of sphericity of 0.827 and a Cronbach Alpha reliability value of 0.969. The Maternal Collapse Case Checklist instrument has a correlation value range of 0.287 – 0.995 with the results of the KMO Barlett test of sphericity of 0.668 and a Cronbach Alpha reliability value of 0.882. There are 2 invalid instrument items, namely Initial Assessment and Transfer Intensive Therapy Unit. Conclusion The Ottawa Crisis Resource Management Global Rating Scale and Maternal Collapse Case Checklist are valid and reliable in Maternal Collapse cases, but some modifications are needed."

"Perubahan kondisi pembebanan dapat mempengaruhi kapasitas dan kemampuan pengiriman daya (power transfer capability) pada sistem tenaga listrik. Ketika kondisi pembebanan rendah, sistem tenaga listrik mengalami tegangan lebih akibat kelebihan suplai daya reaktif pada sistem. Selain itu, kondisi tersebut juga dapat menjadi penyebab penurunan kualitas daya pada saluran akibat deviasi tegangan yang melampaui batas nominal sesuai standar yang berlaku. Oleh sebab itu, peralatan Flexible AC Transmission System (FACTS) diperlukan untuk memperbaiki dan memitigasi permasalahan yang terjadi. Pada penelitian ini, peralatan FACTS yang dipasang yaitu Static VAR Compensator (SVC) dengan tujuan untuk memperbaiki profil tegangan dan tetap menjaga kondisi kestabilan tegangan di sistem transmisi DI Yogyakarta 150 kV ketika kondisi beban rendah Idul Adha 2023. Lokasi pemasangan SVC yang optimal ditentukan melalui Metode Novel Collapse Prediction Index (NCPI). Sementara itu, penentuan kapasitas optimal SVC akan dilakukan dengan beberapa variasi kapasitas TCR dan kemudian divalidasi dengan QV Curve pada busbar yang telah ditentukan. Pada penelitian ini, lokasi pemasangan SVC dilakukan pada tiga lokasi busbar, yaitu KNTUNG/1 dengan kapasitas 161.5696 Mvar, BNTUL/2 dengan kapasitas 180.0023 Mvar, BNTUL/1 dengan kapasitas 245.0698 Mvar. Pemasangan SVC di beberapa lokasi tersebut berhasil menurunkan tegangan sebesar 5.499% pada busbar KNTUNG/1, 7.988% pada busbar BNTUL/2, dan 7.608% pada busbar BNTUL/1. Walaupun kondisi kestabilan tegangan terjaga, pemasangan SVC dapat menurunkan reactive power margin sebesar 20.47331% pada busbar KNTUNG/1, 27.96022% pada busbar BNTUL/2, dan 27.18405% pada busbar BNTUL/1.

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Loading conditions can affect the power system's capacity and power transfer capability. The power system experiences overvoltage in low-loading conditions due to an excess reactive power supply. In addition, this condition can also cause a decrease in power quality on the line due to voltage deviations that exceed nominal limits according to applicable standards. Therefore, Flexible AC Transmission System (FACTS) equipment is needed to improve and mitigate the problems. In this study, the FACTS equipment installed is the Static VAR Compensator (SVC) to improve the voltage profile and maintain voltage stability in the DI Yogyakarta 150 kV transmission system during low load conditions Eid al-Adha 2023. The Novel Collapse Prediction Index (NCPI) method determines the optimal SVC installation location. Meanwhile, the optimal SVC capacity will be determined with several variations of TCR capacity and then validated with the QV Curve on the specified busbar. In this study, the SVC installation location was carried out at three busbar locations, namely KNTUNG/1 with a capacity of 161.5696 Mvar, BNTUL/2 with a capacity of 180.0023 Mvar, BNTUL/1 with a capacity of 245.0698 Mvar. Installing SVC at some locations reduced the voltage by 5.499% at the KNTUNG/1 busbar, 7.988% at the BNTUL/2 busbar, and 7.608% at the BNTUL/1 busbar. Although the voltage stability condition is maintained, the installation of SVC can reduce the reactive power margin by 20.47331% on the KNTUNG/1 busbar, 27.96022% on the BNTUL/2 busbar, and 27.18405% on the BNTUL/1 busbar."

"Adanya gangguan pada sistem tenaga listrik dapat memicu ketidakstabilan tegangan sistem. Ketidakstabilan tegangan sistem dapat menyebabkan runtuh tegangan yang kemudian berakhir dengan black out sebagian ataupun seluruh sistem. Sehingga penting untuk menjaga stabilitas tegangan sistem. Pada skripsi ini dibahas tentang analisis statis dan dinamis stabilitas tegangan sistem tenaga listrik CNOOC SES Ltd. dimana sistem menggunakan skema pelepasan beban undervoltage. Digunakan perangkat lunak ETAP 7.0.0 untuk simulasi aliran daya dan simulasi transient analysispada sistem. Metode kurva Q-V (analisis statis) digunakan sebagai pendekatan pada keadaan operasi normal dengan menggunakan simulasi aliran daya, sedangkan analisis dinamis digunakan pada simulasi transient analysis dengan mengatur lima skenario gangguan besar. Dengan metode kurva Q-V didapatkan bahwa bus beban pada daerah Utara rentan mengalami ketidakstabilan tegangan jika terjadi kenaikan/penambahan beban, sedangkan tegangan bus beban di daerah Selatan dan Tengah lebih stabil. Berdasarkan analisis dinamis, sistem tenaga listrik CNOOC SES Ltd. dapat mengembalikan stabilitas tegangannya setelah dilakukan pelepasan beban undervoltage dengan kapasitas yang berbeda dalam setiap skenario sehingga adanya skema pelepasan beban undervoltage sudah cukup efektif untuk mencegah terjadinya runtuh tegangan (voltage collapse).

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In a power system, disturbances can trigger into instability of system voltage. Instability of system voltage can lead to voltage collapse that ended with the partition or the whole system black out. So, it is important to maintain the system voltage stability. In this paper will be explained about static and dynamic analysis of CNOOC SES Ltd. voltage stability where the system uses undervoltage load shedding scheme. ETAP 7.0.0 software is used to simulate load flow and transient analysis to the system. Q-V curve method (static analysis) is used as an approach to the normal operation condition using load flow simulation, while dynamic analysis is used in transient analysis simulation by setting five large disturbance scenarios.

Using Q-V curve method, obtained that the load buses in the North Area are prone to voltage instability if there is an increase or addition of load, while the load buses in South and Central Area are more voltage stable. Based on dynamic analysis, CNOOC SES Ltd. power system can maintain the voltage stability after holding undervoltage load shedding for different load shedding capacity in each scenario, so the undervolatage load shedding scheme is effective enough to prevent voltage collapse."