Zirconium-titanium-based AB2 is a potential candidate for hydrogen storage alloys and NiMH battery electrodes. Machine learning (ML) has been used to discover and optimize the properties of energy-related materials, including hydrogen storage alloys. This study used ML approaches to analyze the AB2 metal hydrides dataset. The AB2 alloy is considered promising owing to its slightly high hydrogen density and commerciality. This study investigates the effect of the alloying elements on the hydrogen storage properties of the AB2 alloys, i.e., the heat of formation (ΔH), phase abundance, and hydrogen capacity. ML analysis was performed on the 314 pairs collected and data curated from the literature published during 1998–2019, comprising the chemical compositions of alloys and their hydrogen storage properties. The random forest model excellently predicts all hydrogen storage properties for the dataset. Ni provided the most contribution to the change in the enthalpy of the hydride formation but reduced the hydrogen content. Other elements, such as Cr, contribute strongly to the formation of the C14-type Laves phase. Mn significantly affects the hydrogen storage capacity. This study is expected to guide further experimental work to optimize the phase structure of AB2 and its hydrogen sorption properties.

One of the container port performance is the ratio of Effective Time to Berth Time (ET:BT). A thorough study of all the ground handling processes is required to improve it. This study aimed to design proposed improvements to the performance of the ground handling process. Data collection was carried out by direct observation through interviews, as well as measuring time using a stopwatch, and various manual distance measurements. Data obtained were analyzed by using Big Picture Mapping (BPM) followed by Process Activity Mapping (PAM). Activities that categorized to be non-value added (NVA) are examined in detail using the Root Cause Analysis (RCA) method and 5 Why's Analysis. Results obtained are several factors that cause waste. These factors, then, would be reviewed to produce four classifications of improvement recommendations namely scheduling, management, human error and tools/facilities. After knowing the causes of various activities that did not add value to the process, then the improvement proposals were ready to be made.

In a lead acid battery industry, grid casting is a process that has high defect and thickness variation level. DMAIC (Define-Measure-Analyse-Improve-Control) method and its tools will be used to improve the casting process. In the Define stage, it is used project charter and SIPOC (Supplier Input Process Output Customer) method to map the existent problem. In the Measure stage, it is conducted a data retrieval related to the types of defect and the amount of it, also the grid thickness variation that happened. And then the retrieved data is processed and analyzed by using 5 Why’s and FMEA method. In the Analyze stage, it is conducted a grid observation that experience fragile and crack type of defect by using microscope showing the amount of oxide Pb inclusion in the grid. Analysis that is used in grid casting process shows the difference of temperature that is too high between the metal fluid and mold temperature, also the corking process that doesn’t have standard. The Improve stage is conducted a fixing process which generates the reduction of grid variation thickness level and defect/unit level from 9,184% to 0,492%. In Control stage, it is conducted a new working standard determination and already fixed control process.

The performance and life of lead-acid batteries are severely limited due to sulfation in the negative plates. The addition of an appropriate form of carbon as an additive in the negative plate was usually applied to solve the problem. However, previous research conducted showed that lead sulfate is also permanently deposited on positive electrodes. Several other studies have also shown that the addition of carbon to the positive active material successfully increases the life cycle of the battery. This study uses two types of carbon that is self-made activated carbon and acetylene black. The purposes are to increase battery life and to find out more in the variables that control battery life especially the role of carbon in positive electrode. This research begins with the manufacture of activated carbon from charcoal and bought acetylene black. Both types of carbon will then be coated on the battery's positive plates. Testing were done using 8-channel battery analyzer. The results show that the coating using acetylene black gives a better life cycle effect compared to the positive plate coated with activated carbon from coconut shell charcoal and standard plate.

Lead-acid battery is widely used as automotive starting, lighting, and ignition (SLI) batteries. Due to economic of the production and rather simple manufacturing process, the lead-acid battery remains as a feasible type of battery for renewable energy storage application. However, the cycle life of battery is limited to several hundreds of cycles depends on operational conditions. The aim of the present work was to study the effect of depth of discharge (DoD) on the cycle life of a battery which is relevant for battery in renewable energy applications. The battery samples used in the present work were prepared from commercial SLI battery. The sample was cycled in 2 electrode systems at constant current charging and discharging procedure in an Autolab PGSTAT 302 N at different DoD, i.e. 40%, 60%, and 80% for 80 cycles. Scanning Electron Microscope (SEM), X-Ray Diffraction (XRD) were used to characterize active materials after the cycle life test. The cycle test showed a significant formation of lead sulfate (PbSO4) on the negative and positive electrode and the highest level was found at 80% DoD. The sulfation decreased as DoD was reduced. Excessive lead sulfate (PbSO4) formation was found on the negative electrode at all the DoD regimes. This result indicates that decreasing cycle life of valve regulated lead acid (VRLA) battery is mostly caused by sulfation on the negative electrode.

Amonia Feed Pump GA101A merupakan pompa jenis centrifugal multistage dan merupakan salah satu critical equipment pada pabrik urea PT. Petrokimia Gresik. Kegagalan yang terjadi pada pompa GA101A adalah patahnya poros. Patah poros pompa dianalisa dengan melalui beberapa tahapan, yaitu pengamatan makroskopis, melakukan pemodelan CAD, kemudian melakukan analisa Finite Element. Analisa thermal expansion yang dilakukan yakni dengan membandingkan material ring sebelum dan sesudah modifikasi serta mengetahui thermal expansion yang terjadi pada poros. Dari analisa didapatkan mekanisme yang menyebabkan poros pompa GA101A patah, yaitu vibrasi tinggi pada pompa yang menyebabkan gesekan dan kenaikan temperatur melebihi temperatur kerja pompa. Temperatur akibat gesekan menyebabkan ekspansi material kedua komponen, sehingga ring mengunci poros hingga akhirnya patah. Langkah preventif dari hasil analisa adalah memperbesar clearance poros-ring sebesar 0.40mm tanpa mengganti jenis material, yakni Stainless Steel 304, sedangkan jika dengan material Stainless Steel 410 clearance minimal yang dibutuhkan adalah sebesar 0.35mm.

Line A-1011-14”(25P2J) menggunakan pipa tahan karat TP304H berdiameter 14 inch. Pipa mengalami pecah saat beroperasi pada temperatur 800oC (overheating) dan crack ditemukan pada hampir semua sambungan las. Kegagalan pipa dievaluasi dengan metode RCFA (root cause failure analysis) didukung pengujian Metalografi, SEM-EDX, dan OES. Metode ini digunakan untuk mengetahui akar penyebab kegagalan pipa udara TP304H pada line A-1011-14”(25P2J). Hasil analisa didapat adanya pre-existing crack mengakibatkan tegangan pipa 12978.55 psi masih di bawah tensile strength material TP304H pada temperatur 800oC yaitu 18000 psi. Hasil pengujian SEM dan metalografi menyatakan bahwa, kegagalan yang terjadi pada las longitudinal diakibatkan adanya IGSCC (intergranular stress corrosion cracking) yang mengakibatkan batas butir mengalami sliding, dan terjadi penurunan kekuatan pada material. Adanya sensitisasi dibuktikan dengan pengujian EDX yang menunjukkan kenaikan persentase unsur krom dan karbon pada batas butir yaitu 1.4% dan 21.64%. Untuk menghindari kegagalan yang sama, maka material TP304H welded pipe perlu diganti TP304H seamless pipe. Crack yang terjadi pada las circumferential diakibatkan adanya IP (incomplete penetration) yang menyebabkan tumbuhnya crack yang menjalar dari ujung IP menuju fusion zone, untuk mencegah hal tersebut maka setiap proses pengelasan yang dilakukan harus disesuaikan dengan prosedur.