13 results on '"Luinge, Hj"'
Search Results
2. Artificial neural networks as a tool for identity confirmation of infrared spectra
- Author
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Visser T, Luinge HJ, and LOC
- Abstract
Onderzoek is uitgevoerd naar de bruikbaarheid van kunstmatige neurale netwerken als criterium voor de identiteitsbevestiging van infrarood-(IR) spectra. Doel van het onderzoek is de identificatie van spectra met hoge ruisniveaus, verkregen met behulp van gecombineeerde gaschromatografie (GC)IR spectrometrie. Neurale netwerken zijn getraind op GC/IR spectra van Clenbuterol, Fluoranthene en Perylene. De resultaten zijn vergeleken met classificatie door middel van "peak matching-" en bibliotheekzoekprocedures. Peak matching bleek de meest betrouwbare methode voor de identificatie van sterk gelijkende spectra. Voorwaarde is echter een laag ruisniveau en een hoge spectrale resolutie. Dit geldt eveneens voor bibliotheekzoekmethoden. Neurale netwerken bleken minder gevoelig voor ruis en daarom meer geschikt voor bevestiging van de identiteit van IR-spectra van sporenhoeveelheden.
- Published
- 2012
3. INTERACTION, Training and monitoring of daily-life physical interaction with the environment after stroke
- Author
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Veltink, Ph, van Meulen FB, van Beijnum BJF, Hermens, Hj, DE ROSSI, DANILO EMILIO, Lorussi, Federico, Tognetti, Alessandro, Buurke, Jh, Reenalda, J, Baten, Ctm, Simons, Cdm, Luft AR, L, Schepers, Hm, Luinge, Hj, Paradiso, R, and Orselli, R.
- Published
- 2012
4. Artificial neural networks as a tool for identity confirmation of infrared spectra
- Author
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LOC, Visser T, Luinge HJ, LOC, Visser T, and Luinge HJ
- Abstract
RIVM rapport:Onderzoek is uitgevoerd naar de bruikbaarheid van kunstmatige neurale netwerken als criterium voor de identiteitsbevestiging van infrarood-(IR) spectra. Doel van het onderzoek is de identificatie van spectra met hoge ruisniveaus, verkregen met behulp van gecombineeerde gaschromatografie (GC)IR spectrometrie. Neurale netwerken zijn getraind op GC/IR spectra van Clenbuterol, Fluoranthene en Perylene. De resultaten zijn vergeleken met classificatie door middel van "peak matching-" en bibliotheekzoekprocedures. Peak matching bleek de meest betrouwbare methode voor de identificatie van sterk gelijkende spectra. Voorwaarde is echter een laag ruisniveau en een hoge spectrale resolutie. Dit geldt eveneens voor bibliotheekzoekmethoden. Neurale netwerken bleken minder gevoelig voor ruis en daarom meer geschikt voor bevestiging van de identiteit van IR-spectra van sporenhoeveelheden., The utility of artificial neural networks (ANN) as a tool for confirmation of the identity of infrared (IR) spectra has been investigated. The main goal of the study is the identification of spectra with relatively high noise levels, obtained from gas chromatography combined with IR spectrometric detection. Networks were trained for GC/IR spectra of Clenbuterol, Fluoranthene and Perylene as representatives of compounds for which identification in real world samples is demanded occasionally. Results have been compared with classification by peak matching and library search methods. Peak matching appears to be the most discriminative method to distinguish between closely resembling spectra, but only in case of high signal-to-noise ratio and resolution. Similar conclusions are drawn for library search identification. ANN-models are less sensitive to spectral noise and hence most suited to be used for confirmation and identification of spectra obtained intrace analysis.
- Published
- 1995
5. Recognition of visual characteristics of infrared spectra by artificial neural networks and partial least squares regression
- Author
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Visser T, Luinge HJ, Visser T, and Luinge HJ
- Abstract
RIVM rapport:Abstract niet beschikbaar, The usefulness of artificial neural networks (ANN) and partial least squares regression (PLS) for computerized interpretation of infrared (IR) spectra has been studied. Experiments have been carried out to establish the capabilities of these methods to recognize characteristic band shapes and patterns as used for the interpretation by experts. Spectra have been classified by (i) the complete spectral profile (ii) the band pattern in a limited preselected region and (iii) individual band shapes. The results are compared with classifications using computer generated frequency/intensity-structure correlations and as performed by experienced spectroscopists. Classification by skilled interpretators is found to be superior in all cases but a significant improvement of the results from ANN and PLS is established compared with predictions obtained from frequency/intensity-structure correlations. Differences in scores between ANN and PLS were small when full spectra or limited spectral regions are considered. Networks scored better in recognizing individual bands. Both the absorption frequency and the band width play an important role in the recognition process.
- Published
- 1993
6. Herkennen van visuele aspecten van infraroodspectra met neurale netwerken
- Author
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Reinders A, Visser T, Roos D, Vink PJF de, Luinge HJ, Reinders A, Visser T, Roos D, Vink PJF de, and Luinge HJ
- Abstract
RIVM rapport:Abstract niet beschikbaar, This document describes how neural networks can be trained to classify and recognize infrared spectra. Backpropagation was used as the neural network type. The effect of noise on the recognition capabilities of a network has been investigated by generating 150 spectra with various noise levels out of 3 standard spectra. The trained network appeared to be capable of recognizing spectra correctly up to a noise level of 70%. Recognition appears to be correct up to a noise lebel of 70%. The classifying capabilities of backpropagation of spectra have been studied by training a network with 30 spectra, equally divided over three classes. Fourteen other spectra were used as a control set. Only one spectrum was found to be incorrectly classified. The preliminary conclusion is that neural networks are a useful addition to standard pattern matching techniques, especially for recognizing visual aspects.
- Published
- 1991
7. Ambulatory measurement of arm orientation.
- Author
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Luinge HJ, Veltink PH, and Baten CT
- Subjects
- Acceleration, Activities of Daily Living, Algorithms, Arm anatomy & histology, Biomechanical Phenomena, Female, Humans, Models, Anatomic, Models, Biological, Arm physiology
- Abstract
In order to evaluate the impact of neuromuscular disorders affecting the upper extremities, the functional use of the arm need to be evaluated during daily activities. A system suitable for measuring arm kinematics should be ambulatory and not interfere with activities of daily living. A measurement system based on miniature accelerometers and gyroscopes is adequate because the sensors are small and do not suffer from line of sight problems. A disadvantage of such sensors is the cumulative drift around the vertical and the problems with aligning the sensor with the segment. A method that uses constraints in the elbow to measure the orientation of the lower arm with respect to the upper arm is described. This requires a calibration method to determine the exact orientation of each of the sensors with respect to the segment. Some preliminary measurements were analyzed and they indicated a strong reduction in orientation error around the vertical. It seemed that the accuracy of the method is limited by the accuracy of the sensor to segment calibration.
- Published
- 2007
- Full Text
- View/download PDF
8. Compensation of magnetic disturbances improves inertial and magnetic sensing of human body segment orientation.
- Author
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Roetenberg D, Luinge HJ, Baten CT, and Veltink PH
- Subjects
- Artifacts, Computer Simulation, Humans, Range of Motion, Articular physiology, Acceleration, Algorithms, Diagnosis, Computer-Assisted methods, Joints physiology, Magnetics, Models, Biological, Movement physiology, Posture physiology
- Abstract
This paper describes a complementary Kalman filter design to estimate orientation of human body segments by fusing gyroscope, accelerometer, and magnetometer signals from miniature sensors. Ferromagnetic materials or other magnetic fields near the sensor module disturb the local earth magnetic field and, therefore, the orientation estimation, which impedes many (ambulatory) applications. In the filter, the gyroscope bias error, orientation error, and magnetic disturbance error are estimated. The filter was tested under quasi-static and dynamic conditions with ferromagnetic materials close to the sensor module. The quasi-static experiments implied static positions and rotations around the three axes. In the dynamic experiments, three-dimensional rotations were performed near a metal tool case. The orientation estimated by the filter was compared with the orientation obtained with an optical reference system Vicon. Results show accurate and drift-free orientation estimates. The compensation results in a significant difference (p < 0.01) between the orientation estimates with compensation of magnetic disturbances in comparison to no compensation or only gyroscopes. The average static error was 1.4 degrees (standard deviation 0.4) in the magnetically disturbed experiments. The dynamic error was 2.6 degrees root means square.
- Published
- 2005
- Full Text
- View/download PDF
9. Measuring orientation of human body segments using miniature gyroscopes and accelerometers.
- Author
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Luinge HJ and Veltink PH
- Subjects
- Acceleration, Biomechanical Phenomena, Humans, Models, Biological, Signal Processing, Computer-Assisted, Monitoring, Ambulatory methods, Movement physiology, Orientation physiology
- Abstract
In the medical field, there is a need for small ambulatory sensor systems for measuring the kinematics of body segments. Current methods for ambulatory measurement of body orientation have limited accuracy when the body moves. The aim of the paper was to develop and validate a method for accurate measurement of the orientation of human body segments using an inertial measurement unit (IMU). An IMU containing three single-axis accelerometers and three single-axis micromachined gyroscopes was assembled in a rectangular box, sized 20 x 20 x 30 mm. The presented orientation estimation algorithm continuously corrected orientation estimates obtained by mathematical integration of the 3D angular velocity measured using the gyroscopes. The correction was performed using an inclination estimate continuously obtained using the signal of the 3D accelerometer. This reduces the integration drift that originates from errors in the angular velocity signal. In addition, the gyroscope offset was continuously recalibrated. The method was realised using a Kalman filter that took into account the spectra of the signals involved as well as a fluctuating gyroscope offset. The method was tested for movements of the pelvis, trunk and forearm. Although the problem of integration drift around the global vertical continuously increased in the order of 0.50 degrees s(-1), the inclination estimate was accurate within 3 degrees RMS. It was shown that the gyroscope offset could be estimated continuously during a trial. Using an initial offset error of 1 rad s(-1), after 2 min the off-set error was roughly 5% of the original offset error. Using the Kalman filter described, an accurate and robust system for ambulatory motion recording can be realised.
- Published
- 2005
- Full Text
- View/download PDF
10. Inclination measurement of human movement using a 3-D accelerometer with autocalibration.
- Author
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Luinge HJ and Veltink PH
- Subjects
- Acceleration, Calibration, Gravitation, Humans, Reproducibility of Results, Sensitivity and Specificity, Spine physiology, Task Performance and Analysis, Thorax physiology, Algorithms, Lifting, Monitoring, Ambulatory instrumentation, Monitoring, Ambulatory methods, Movement physiology, Posture physiology, Signal Processing, Computer-Assisted, Transducers
- Abstract
In the medical field, accelerometers are often used for measuring inclination of body segments and activity of daily living (ADL) because they are small and require little power. A drawback of using accelerometers is the poor quality of inclination estimate for movements with large accelerations. This paper describes the design and performance of a Kalman filter to estimate inclination from the signals of a triaxial accelerometer. This design is based on assumptions concerning the frequency content of the acceleration of the movement that is measured, the knowledge that the magnitude of the gravity is 1 g and taking into account a fluctuating sensor offset. It is shown that for measuring trunk and pelvis inclination during the functional three-dimensional activity of stacking crates, the inclination error that is made is approximately 20 root-mean square. This is nearly twice as accurate as compared to current methods based on low-pass filtering of accelerometer signals.
- Published
- 2004
- Full Text
- View/download PDF
11. Determination of acetone in cow milk by Fourier transform infrared spectroscopy for the detection of subclinical ketosis.
- Author
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Heuer C, Luinge HJ, Lutz ET, Schukken YH, van der Maas JH, Wilmink H, and Noordhuizen JP
- Subjects
- Animals, Cattle physiology, Female, Ketosis diagnosis, Models, Biological, Reproducibility of Results, Acetone analysis, Cattle Diseases diagnosis, Ketosis veterinary, Milk chemistry, Spectroscopy, Fourier Transform Infrared methods
- Abstract
Fourier transform infrared analysis (FTIR) was used in combination with partial least squares regression (PLS) to predict the concentration of acetone in milk. FTIR spectra were compared with results of a gas-chromatographic head space method. Principal component analysis of whole spectra (3000 to 1000 cm(-1)) suggested to reduce the spectrum of analysis for acetone to 1450 to 1200 cm(-1). A second derivative was applied to the spectra to remove baseline effects and further enhance the spectral features. Full cross-validation was used to compare the reference with predicted acetone concentrations of samples not included in model development. PLS applied to the full spectral range resulted in a complex 19-factor model with a cross-validation error of 0.22 mM. After reducing the spectrum and taking the second derivative, we obtained a model with seven factors that yielded a cross-validation error of 0.21 mM. This compares favorably with a previously reported model with 20 factors and an error of 0.25 mM. Using PLS predictions to identify cows with subclinical ketosis resulted in 95 to 100% sensitivity and 96 to 100% specificity when the threshold for subclinical ketosis was 0.4 to 1.0 mM. The corresponding positive predictive values were > or = 76% and the negative predictive values > 98% throughout an assumed range of subclinical ketosis prevalence of 10 to 30%.
- Published
- 2001
- Full Text
- View/download PDF
12. Estimating orientation with gyroscopes and accelerometers.
- Author
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Luinge HJ, Veltink PH, and Baten CT
- Subjects
- Algorithms, Biomechanical Phenomena, Biomedical Engineering instrumentation, Humans, Computer Simulation, Kinesthesis physiology, Posture physiology
- Published
- 1999
13. Statistical analysis of mass spectral data obtained from singly protonated peptides under high-energy collision-induced dissociation conditions.
- Author
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van Dongen WD, Ruijters HF, Luinge HJ, Heerma W, and Haverkamp J
- Subjects
- Amino Acids chemistry, Data Interpretation, Statistical, Mass Spectrometry, Protons, Xenon chemistry, Peptides chemistry
- Abstract
A statistical study of the fragmentation behaviour of 138 model peptides, containing 3-9 amino acid residues (n = 3-9) under high-energy collision conditions is presented. The aim was to identify characteristic patterns of ions in the spectra of peptides which can be translated into general rules to be used in the spectral interpretation and provide a better insight into their fragmentation behaviour. It was found that both number and nature of the amino acids are important factors directing the fragmentation behaviour. The spectra of tri- and tetrapeptides exhibit a comparable probability for the formation of B2- and Y"n-2 ions, whereas larger peptides show a preference for the formation of Bn-1 ions. This generally observed fragmentation pattern of peptides is changed significantly when basic amino acid residues (Arg, Lys and His) and/or Pro are present Arginine appears to have the most pronounced influence on the fragmentation behaviour and overrules that of the other amino acid residues.
- Published
- 1996
- Full Text
- View/download PDF
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