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All Journal Bulletin of Electrical Engineering and Informatics Journal of Mathematical and Fundamental Sciences Journal of Engineering and Technological Sciences
Harijono A. Tjokronegoro
Engineering Physics Research Group, Institut Teknologi Bandung
Astronomy Chemistry Earth & Planetary Sciences Electrical & Electronics Engineering Engineering Mathematics Physics

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On Active Surge Control of Compression Systems via Characteristic Linearization and Model Nonlinearity Cancellation Simamora, Yohannes S.M.; Tjokronegoro, Harijono A.; Leksono, Edi
Journal of Engineering and Technological Sciences Vol 46, No 3 (2014)
Publisher : ITB Journal Publisher, LPPM ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1139.257 KB) | DOI: 10.5614/j.eng.technol.sci.2014.46.3.8

Abstract

A simple approach of active surge control of compression systems is presented. Specifically, nonlinear components of the pressure ratio and rotating speed states of the Moore-Greitzer model are transferred into the input vectors. Subsequently, the compressor characteristic is linearized into two modes, which describe the stable region and the unstable region respectively. As a result, the system’s state and input matrices both appear linear, to which linear realization and analysis are applicable. A linear quadratic regulator plus integrator is then chosen as closed-loop controller. By simulation it was shown that the modified model and characteristics can describe surge behavior, while the closed-loop controller can stabilize the system in the unstable operating region. The last-mentioned was achieved when massflow was 5.38 per cent less than the surge point.
Analysis of Onstage Acoustics Preference of Musicians of Traditional Performance of Javanese Gamelan Based on Normalized Autocorrelation Function Suyatno, Suyatno; Tjokronegoro, Harijono A.; Merthayasa, I Gede Nyoman; Supanggah, Rahayu
Journal of Engineering and Technological Sciences Vol 48, No 5 (2016)
Publisher : ITB Journal Publisher, LPPM ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1531.605 KB) | DOI: 10.5614/j.eng.technol.sci.2016.48.5.5

Abstract

On-stage sound field analysis of a traditional performance of the Javanese gamelan at Pendopo ISI Surakarta, Indonesia was conducted by analyzing the effective decay time of a normalized autocorrelation function called tau-e, τe , during a performance of the Gambyong Pare Anom dance. The parameter tau-e is used to describe the richness of the frequency content, tempo, and types of gamelan instruments being played at a certain time and position on stage. The tau-e parameter is important for musicians in order to maintain communication between each other such that they can keep the performance in harmony. In order to determine the acoustic parameters heard by gamelan musicians on stage, sound measurements were conducted at 4 points on stage during a performance. Each position represents a specific group of gamelan instruments, which have different characteristics of loudness and frequency, different functions and different ways the instruments are played. The analysis showed that each of the four positions had a different value of τe , which fluctuated throughout the performance. Overall, the dominant τe at position 1 was 20 ms; at position 2 it was 50 ms; at position 3 it was 20 ms; and at position 4 it was 40 ms. The distribution of τe on the stage shows that positions 1 and 3 had more frequency richness compared to positions 2 and 4.
Compensation of time-varying clock-offset in a LBL navigation Yohannes S. M. Simamora; Harijono A. Tjokronegoro; Edi Leksono; Irsan S. Brodjonegoro
Bulletin of Electrical Engineering and Informatics Vol 9, No 4: August 2020
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (5316.737 KB) | DOI: 10.11591/eei.v9i4.1996

Abstract

This paper presents compensation of the clock-offset in a long baseline (LBL)navigation. It departs from the existing literature mainly in dealing with a time-varyingclock-offset, i.e. the clock-rate drifts over the time. Specifically, the clock-offsetdynamics are introduced to the ToFs as an autoregressive filter.Subsequently,interactions among the now biased ToFs and the kinematics of an autonomousunderwater vehicle (AUV)–the navigation subject–are represented in a state-spaceform. Implementing the so-called graphic approach, minimum sensor requirementfor this system’s observability is then explicated. Finally, a standard discrete Kalmanfilter is deployed as the state estimator. By simulation, it is demonstrated that theestimator manages to compensate the offset and to provide localization with less than1 m accuracy
On Active Surge Control of Compression Systems via Characteristic Linearization and Model Nonlinearity Cancellation Yohannes S.M. Simamora; Harijono A. Tjokronegoro; Edi Leksono
Journal of Engineering and Technological Sciences Vol. 46 No. 3 (2014)
Publisher : Institute for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2014.46.3.8

Abstract

A simple approach of active surge control of compression systems is presented. Specifically, nonlinear components of the pressure ratio and rotating speed states of the Moore-Greitzer model are transferred into the input vectors. Subsequently, the compressor characteristic is linearized into two modes, which describe the stable region and the unstable region respectively. As a result, the system's state and input matrices both appear linear, to which linear realization and analysis are applicable. A linear quadratic regulator plus integrator is then chosen as closed-loop controller. By simulation it was shown that the modified model and characteristics can describe surge behavior, while the closed-loop controller can stabilize the system in the unstable operating region. The last-mentioned was achieved when massflow was 5.38 per cent less than the surge point.
Analysis of Onstage Acoustics Preference of Musicians of Traditional Performance of Javanese Gamelan Based on Normalized Autocorrelation Function Suyatno Suyatno; Harijono A. Tjokronegoro; I Gede Nyoman Merthayasa; Rahayu Supanggah
Journal of Engineering and Technological Sciences Vol. 48 No. 5 (2016)
Publisher : Institute for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2016.48.5.5

Abstract

On-stage sound field analysis of a traditional performance of the Javanese gamelan at Pendopo ISI Surakarta, Indonesia was conducted by analyzing the effective decay time of a normalized autocorrelation function called tau-e, Ï„e , during a performance of the Gambyong Pare Anom dance. The parameter tau-e is used to describe the richness of the frequency content, tempo, and types of gamelan instruments being played at a certain time and position on stage. The tau-e parameter is important for musicians in order to maintain communication between each other such that they can keep the performance in harmony. In order to determine the acoustic parameters heard by gamelan musicians on stage, sound measurements were conducted at 4 points on stage during a performance. Each position represents a specific group of gamelan instruments, which have different characteristics of loudness and frequency, different functions and different ways the instruments are played. The analysis showed that each of the four positions had a different value of Ï„e , which fluctuated throughout the performance. Overall, the dominant Ï„e at position 1 was 20 ms; at position 2 it was 50 ms; at position 3 it was 20 ms; and at position 4 it was 40 ms. The distribution of Ï„e on the stage shows that positions 1 and 3 had more frequency richness compared to positions 2 and 4.
Compensation of INS/LBL Navigation Errors in a Polynomial Sound-Speed-Profile Yohannes Sampang Martua Simamora; Harijono A. Tjokronegoro; Edi Leksono; Irsan S. Brodjonegoro
Journal of Engineering and Technological Sciences Vol. 54 No. 2 (2022)
Publisher : Institute for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2022.54.2.11

Abstract

This paper presents an autonomous underwater vehicle (AUV) navigation scheme that pairs an inertial navigation system (INS) and a long baseline (LBL) acoustic positioning system. The INS is assigned to be the main navigation aid because of its faster rate. Meanwhile, the LBL provides position reference for compensation of the INS’ main inherent drawback, i.e., accumulating errors. However, the LBL has to deal with time-of-flight (ToF) measurements that may not be carried out under line-of-sight (LoS) circumstances. This is because the propagation speed of underwater acoustic waves is subject to the sound-speed-profile (SSP) of the area in question. This paper’s contribution is to consider the SSP in ToFs while addressing the above scheme. Specifically, the discrete approach to raytracing was implemented. For a given ToF, the Snell’s parameter of the wave is estimated and subsequently used to compute the horizontal range. The ToF results are then used to estimate the position of the AUV, while the  position is obtained from a depth sensor. It was shown by simulation that the estimators can provide navigation with accuracy <0.5 m2, as it manages to compensate for errors. Since the estimation of Snell’s parameter is prone to exhibit imaginary numbers, future work should consider a more robust method to tackle this problem.
Estimasi Model Parametrik Komponen Feedback, Feedforward, dan Nois pada Sistem Lup Tertutup dengan Teknik Extended Least Square Harijono A. Tjokronegoro
Journal of Mathematical and Fundamental Sciences Vol. 35 No. 1 (2003)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.sci.2003.35.1.1

Abstract

In this paper is considered a direct estimation technique of model parameters of components (subsystems) of a feedback system using an extended least squares algorithm. There are three components of system may be estimated, feedback, feedforward, and noise. It has been assumed that the system considered was linear and time invariant. A common estimation technique for closed loop system is indirect, and under assumption that only one component will be estimated while the other components in the closed loop are known. The analysis shows that the proposed technique is unnbias. In the proposed structure, one of the components in the closed loop system maybe unstable, as long as the closed loop system is stable.
Computational Scheme for Geosynchronous Satellite Orbit due to Gravitation of the Earth Harijono Djojodiharjo; Yus Kadarusman
Journal of Mathematical and Fundamental Sciences Vol. 15 No. 3 (1982)
Publisher : Institute for Research and Community Services (LPPM) ITB

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Abstract

By analyzing the influence of the earth's gravitational anomaly on the orbit of a satellite around the earth, a computational scheme for geosynchronous satellite orbit with small inclination is developed. The governing equations of motion, which consist of three equations and have been simplified to take into account geosynchronous conditions and small displacements, are solved by numerical technique. In particular the radius of geosynchronous orbit is obtained by solving the first governing equation by Regula-Falsi method. Stationary points are obtained by indirect method, i.e. by first finding the longitude positions with zero longitudinal accelerations. The trajectory of the subsatellite point is obtained by solving the governing equations for small displacement by Runge-Kutta method. Comparison of computational result with Blitzer's and Flury's using IAU 1968 and GEM-8 data, leads confidence to the present scheme.
Vinti's Surface Density as a Means of Representing the Earth's Disturbance Potential Harijono Djojodihardjo
Journal of Mathematical and Fundamental Sciences Vol. 7 No. 4 (1974)
Publisher : Institute for Research and Community Services (LPPM) ITB

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Abstract

Abstract. Vinti's method of representing the potential of the earth in two parts, with the first part represented by spheroidal potential and the second part being the earth disturbance potential, is outlined. The earth's disturbance potential is then represented as a surface distribution σ of mass density of variable sign over a sphere S just clearing the earth. The feasibility of the method is evaluated by calculating the distribution of o from satellite determination of the harmonic coefficients. Ringkasan. Suatu metoda untuk menyatakan potensial bumi berdasarkan teori Vinti diuraikan. Menurut metoda ini, potensial bumi dinyatakan sebagai jumlah potensial utama, yang diperoleh sebagai potensial spheroid, dan potensial gangguan, yang dinyatakan sebagai distribusi kerapatan masa permukaan pada suatu bola yang tepat menyelubungi bumi. Kegunaan metoda ini diuji dengan menghitung distribusi σ dengan menggunakan koefisien-koefisien harmonik yang ditentukan dari analisa data satelit.
Some Notes on the Design, Construction and Performance of the Low-Speed Wind-Tunnel at ITB Harijono Djojodihardjo
Journal of Mathematical and Fundamental Sciences Vol. 7 No. 3 (1973)
Publisher : Institute for Research and Community Services (LPPM) ITB

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Abstract

Abstract. A concise description of the design and construction of the low speed wind-tunnel at Institut Teknologi Bandung and the calculation of its energy losses are presented. Some tests have been undertaken to evaluate its performance, in particular to evaluate the flow pattern at the test-section and the power input for a specific range of wind velocity at the test-section. The maximum velocity achieved at the test-section was 30 m/sec with corresponding Reynolds number of 2 x 104 per cm.  Ringkasan. Konstruksi dan perhitungan kerugian energi  pada terowongan angin kecepatan rendah di ITB diuraikan secara garis besar. Selanjutnya dipaparkan hasil-hasil penilaian performance dari terowongan angin ini, terutama mengenai keadaan aliran pada testsectiondan hubungan antara daya input pada motor dengan kecepatan aliran pada test-section. Kecepatan angin sebesar 30 m/det dapat diperoleh pada test-section, dengan bilangan Reynolds sebesar 2 x 104 per cm model.
Co-Authors Edi Leksono I Gede Nyoman Merthayasa Irsan S. Brodjonegoro Irsan S. Brodjonegoro Jasa, Zafrullah Kany Merthayasa, I Gede Nyoman Rahayu Supanggah Rehatta, Nancy Margareta Saleh, Siti Chasnak Santosa, Dhania Anindita SATRIYAS ILYAS Supanggah, Rahayu Suyatno Suyatno Suyatno, Suyatno Wohon, Erfprinsi Yohannes S.M. Simamora Yohannes Sampang Martua Simamora Yus Kadarusman