Fouling Mitigation for Laser Igniters in Natural Gas Engines

Due to several recent developments in lasers and optics, laser igniters can now be designed to be (i) compact so as to have the same footprint as a standard spark plug, (ii) have low power draw, usually less than 50 Watts, and (iii) have vibration and temperature resistance at levels typical of reciprocating engines. Primary advantages of these laser igniters remain (i) extension of lean or dilution limits for ignition of combustible mixtures, and (ii) improved ignition at higher pressures. Recently, tests performed in a 350 kW 6-cylinder stationary natural gas reciprocating engine retrofitted with these igniters showed an extension of the operational envelope to yield efficiency improvements of the order of 2.6% points while being compliant with the mandated emission regulations. Even though laser igniters offer promise, fouling of the final optical element that introduces the laser into the combustion chamber is of concern. After performing a thorough literature search, a test plan was devised to evaluate various fouling mitigation strategies. The final approach that was used is a combination of three strategies and helped sustain an optical transmissivity exceeding 98% even after 1500 hrs. of continuous engine operation at 2400 rpm. Based on the observed trend in transmissivity, it now appears that laser igniters can last up to 6000 hrs. of continuous engine operation in a stationary engine running at 1800 rpm.

GREEN ACCOUNTING: PEMANFAATAN BANK SAMPAH UNTUK MENINGKATKAN PEREKONOMIAN MASYARAKAT DI BANK SAMPAH UNILAK RIAU

ABSTRAK Salah satu permasalahan besar yang dialami kota-kota besar di Indonesia adalah persampahan. Sampah dapat diartikan sebagai konsekuensi adanya aktivitas kehidupan manusia.Tidak dapat dipungkiri, sampah akan selalu ada selama aktivitas kehidupan masih terus berjalan. Setiap tahunnya, dapat dipastikan volume sampah akan selalu bertambah seiring dengan pola konsumerisme masyarakat yang semakin meningkat. Kementerian Lingkungan Hidup mencatat rata-rata penduduk Indonesia menghasilkan sekitar 2,5 liter sampah per hari atau 625 juta liter dari jumlah total penduduk. Abdimas ini bertujuan agar mengubah mindset Mitra tentang paradigma pengelolaan sampah yang bertumpu pada pendekatan akhir sudah saatnya ditinggalkan dan diganti dengan paradigma baru. Paradigma yang menganggap sampah sebagai sumber daya yang mempunyai nilai ekonomis dan dapat dimanfaatkan, misalnya, untuk energi, kompos, pupuk, dan bahan baku industri. Pengelolaan sampah dapat dilakukan dengan pendekatan yang komprehensif. Dimulai dari hulu, yaitu sejak suatu produk yang berpotensi menjadi sampah belum dihasilkan. Dilanjutkan sampai ke hilir, yaitu pada fase produk sudah digunakan, sehingga menjadi sampah, yang kemudian dikembalikan ke media lingkungan secara aman. Tujuannya agar dapat mengurangi sampah di TPS/TPA dan mendorong pemberdayaan ekonomi masyarakat, melalui pemanfaatan sampah dengan program 3R (Reduce, Reuse dan Recycle). Kata Kunci: Green Accounting, Bank Sampah, Perekonomian ABSTRACT One of the big problems faced by big cities in Indonesia is solid waste. Garbage can be interpreted as a consequence of the activities of human life. It is undeniable that garbage will always exist as long as life activities continue. Every year, it is certain that the volume of waste will always increase along with the increasing consumerism of society. The Ministry of Environment noted that the average Indonesian population produces around 2.5 liters of waste per day or 625 million liters of the total population. This Abdimas aims to change Mitra's mindset about the waste management paradigm that is based on the final approach, it is time to leave it and replace it with a new paradigm. The paradigm that considers waste as a resource that has economic value and can be used, for example, for energy, compost, fertilizer, and industrial raw materials. Waste management can be done with a comprehensive approach. Starting from upstream, that is, since a product that has the potential to become waste has not been produced. Continued downstream, where the product has been used, so that it becomes waste, which is then returned to the environmental media safely. The goal is to reduce waste in TPS/TPA and encourage community economic empowerment, through the use of waste with the 3R (Reduce, Reuse and Recycle) program. Keywords: Green Accounting, Waste Bank, Economy

Hypergraph Application on Business Process Performance

The modeling of the graphical representation of business processes (BP) or workflows in enterprise information systems (IS) is often to represent various activities, entities, relations, functions, and communicate between them in an enterprise to achieve the major goal of operational support. In this work, we decided to use graph representation approaches, especially hypergraphs to depict the complex relationships that exist among the artifacts and constituents of BP for more efficient and accurate manipulations. We used bipartite and further hypergraph formats for storing and curating data. We have investigated the various descriptive languages and representation models of BP as process modeling, workflow and process integration, and object-oriented (OO) languages. We have carried out experiments using different approach combinations, but for observing quiltedrepresentation, we focused on the main consistencies of “DBP”. As the final approach, we used the “DBP” stream and data schemes that are defined by us to proceed with using pure Python for manually generating data and external Python libraries to store, curate, and visualize “DBP”.

Calculation and Analysis of Aircraft Pollutant Emission Based on Time Wake Separation Mode under Coastal Airport and Headwind Conditions

During the final approach, the headwind leads to a reduction of landing rate, which affects the achieved capacity and the predictability of operation, time, fuel efficiency, and environmental pollution. Under headwind conditions, ground speed decrease results in increased flight time. Time-based separation (TBS) changes the separation rule of the final approach, which changes the distance separation between two aircrafts into a time separation. This paper introduces the time-based separation (TBS) based on the distance-based separation (DBS). According to the aircraft landing schedule of each airport, the ICAO (International Civil Aviation Organization) aircraft engine emission database, Boeing Fuel Flow Method 2 (BFFM2), and meteorological data of Pu-dong airport, this study uses the modified P3-T3 aviation pollutant emission model to calculate, respectively, the fuel consumption and pollutant emissions based on distance separation mode and time separation mode. According to the calculation results, TBS operation mode can save 32.52%, 19.12%, and 30.41% fuel, reduce 28.93%, 17.9%, and 29.29% CO, 31.02%, 19.36%, and 33.78% HC, 30.85%, 16.42%, and 28.67% NOx, respectively, compared with the DBS operation mode at three stages of the day. It ends that TBS has an obvious optimization effect on fuel consumption and pollutant emission compared with DBS from data.

Benefits Derived from Arrival Management and Wake Turbulence Re-Categorization in China

Air traffic administration requires evidence when promoting new technology or a new concept of operation. Therefore, when decision support tools are applied, it is necessary to analyze the costs and benefits quantitatively. This paper focuses on the evaluation of Key Performance Indicators (KPIs) correlated with the improvement of arrival operations after the implementation of the Arrival Management (AMAN) system and Wake Turbulence Re-categorization in China (RECAT-CN). Firstly, we give an overview of the implementation of the AMAN system and RECAT in China. Secondly, the KPIs related to the arrival operation are established according to the characteristics of AMAN and RECAT-CN, based on the existing KPI systems in the field of Air Traffic Management (ATM). The proposed KPIs are: airport acceptance rate; final approach interval; flight time within the terminal area (TMA); and taxi-in time. Thirdly, arrival operation within the TMA around Guangzhou International Airport is used as an example to carry out the quantitative analysis. The region and time range were defined for the performance comparison, and external factors were also examined. Finally, using descriptive and inferential statistics, the proposed KPIs’ comparison results are presented and visualized. Such results indicate a significant improvement in arrival operation with the AMAN system and RECAT-CN at Guangzhou International Airport.