---
_id: '61014'
abstract:
- lang: eng
  text: '<jats:p>To obtain a more comprehensive understanding of the specific properties
    of complex-shaped technical aerosols—such as partially sintered aggregates formed
    in combustion processes or structured particles resulting from complex synthesis
    processes—it is essential to measure more than a single equivalent size. This
    study examines a novel method for determining a two-dimensional distribution of
    two distinct particle properties within the size range from 50nm to 1000nm: the
    Centrifugal Differential Mobility Analyzer (CDMA). The CDMA enables the simultaneous
    measurement of both mobility and Stokes equivalent diameters, providing a detailed
    two-dimensional particle property distribution. This, in turn, allows for the
    extraction of shape-related information, which is essential for characterizing
    particles in terms of their chemical composition, reactivity, and other physicochemical
    properties. This paper presents a detailed evaluation of a first CDMA prototype.
    First, CFD simulations of the flow field within the classifier are presented in
    order to assess and understand non-idealities arising from the exact geometry.
    Subsequently, the transfer function is evaluated by particle trajectory calculations
    based on the simulated flow field. It can be demonstrated that the simulated transfer
    functions agree quite well with transfer functions derived from streamlines of
    an ideal flow field, indicating that the non-idealities in the classifying region
    are almost negligible in their effect on the classification result. An experimental
    determination of the transfer function shows additional effects not covered by
    the previous simulations, like broadening by diffusion and losses due to diffusion
    and precipitation within the in- and outlet of the classifier. Finally, the determined
    transfer functions are used to determine the full two-dimensional distribution
    with regard to the mobility and Stokes equivalent diameter of real aerosols, like
    spherical particles and aggregates at different sintering stages, respectively.</jats:p>'
article_number: '11'
article_type: original
author:
- first_name: Torben Norbert
  full_name: Rüther, Torben Norbert
  last_name: Rüther
- first_name: Sebastian
  full_name: Gröne, Sebastian
  last_name: Gröne
- first_name: Christopher
  full_name: Dechert, Christopher
  last_name: Dechert
- first_name: Hans-Joachim
  full_name: Schmid, Hans-Joachim
  id: '464'
  last_name: Schmid
  orcid: 000-0001-8590-1921
citation:
  ama: Rüther TN, Gröne S, Dechert C, Schmid H-J. Centrifugal Differential Mobility
    Analysis—Validation and First Two-Dimensional Measurements. <i>Powders</i>. 2025;4(2).
    doi:<a href="https://doi.org/10.3390/powders4020011">10.3390/powders4020011</a>
  apa: Rüther, T. N., Gröne, S., Dechert, C., &#38; Schmid, H.-J. (2025). Centrifugal
    Differential Mobility Analysis—Validation and First Two-Dimensional Measurements.
    <i>Powders</i>, <i>4</i>(2), Article 11. <a href="https://doi.org/10.3390/powders4020011">https://doi.org/10.3390/powders4020011</a>
  bibtex: '@article{Rüther_Gröne_Dechert_Schmid_2025, title={Centrifugal Differential
    Mobility Analysis—Validation and First Two-Dimensional Measurements}, volume={4},
    DOI={<a href="https://doi.org/10.3390/powders4020011">10.3390/powders4020011</a>},
    number={211}, journal={Powders}, publisher={MDPI AG}, author={Rüther, Torben Norbert
    and Gröne, Sebastian and Dechert, Christopher and Schmid, Hans-Joachim}, year={2025}
    }'
  chicago: Rüther, Torben Norbert, Sebastian Gröne, Christopher Dechert, and Hans-Joachim
    Schmid. “Centrifugal Differential Mobility Analysis—Validation and First Two-Dimensional
    Measurements.” <i>Powders</i> 4, no. 2 (2025). <a href="https://doi.org/10.3390/powders4020011">https://doi.org/10.3390/powders4020011</a>.
  ieee: 'T. N. Rüther, S. Gröne, C. Dechert, and H.-J. Schmid, “Centrifugal Differential
    Mobility Analysis—Validation and First Two-Dimensional Measurements,” <i>Powders</i>,
    vol. 4, no. 2, Art. no. 11, 2025, doi: <a href="https://doi.org/10.3390/powders4020011">10.3390/powders4020011</a>.'
  mla: Rüther, Torben Norbert, et al. “Centrifugal Differential Mobility Analysis—Validation
    and First Two-Dimensional Measurements.” <i>Powders</i>, vol. 4, no. 2, 11, MDPI
    AG, 2025, doi:<a href="https://doi.org/10.3390/powders4020011">10.3390/powders4020011</a>.
  short: T.N. Rüther, S. Gröne, C. Dechert, H.-J. Schmid, Powders 4 (2025).
date_created: 2025-08-25T16:10:45Z
date_updated: 2025-08-25T16:15:41Z
doi: 10.3390/powders4020011
funded_apc: '1'
intvolume: '         4'
issue: '2'
keyword:
- centrifugal differential mobility analysis
- 2D-measurement
- particle characterization
- moving reference frame CFD-simulation
- transfer function
language:
- iso: eng
publication: Powders
publication_identifier:
  issn:
  - 2674-0516
publication_status: published
publisher: MDPI AG
quality_controlled: '1'
status: public
title: Centrifugal Differential Mobility Analysis—Validation and First Two-Dimensional
  Measurements
type: journal_article
user_id: '464'
volume: 4
year: '2025'
...
---
_id: '11850'
abstract:
- lang: eng
  text: In this paper, we present a novel blocking matrix and fixed beamformer design
    for a generalized sidelobe canceler for speech enhancement in a reverberant enclosure.
    They are based on a new method for estimating the acoustical transfer function
    ratios in the presence of stationary noise. The estimation method relies on solving
    a generalized eigenvalue problem in each frequency bin. An adaptive eigenvector
    tracking utilizing the power iteration method is employed and shown to achieve
    a high convergence speed. Simulation results demonstrate that the proposed beamformer
    leads to better noise and interference reduction and reduced speech distortions
    compared to other blocking matrix designs from the literature.
author:
- first_name: Alexander
  full_name: Krueger, Alexander
  last_name: Krueger
- first_name: Ernst
  full_name: Warsitz, Ernst
  last_name: Warsitz
- first_name: Reinhold
  full_name: Haeb-Umbach, Reinhold
  id: '242'
  last_name: Haeb-Umbach
citation:
  ama: Krueger A, Warsitz E, Haeb-Umbach R. Speech Enhancement With a GSC-Like Structure
    Employing Eigenvector-Based Transfer Function Ratios Estimation. <i>IEEE Transactions
    on Audio, Speech, and Language Processing</i>. 2011;19(1):206-219. doi:<a href="https://doi.org/10.1109/TASL.2010.2047324">10.1109/TASL.2010.2047324</a>
  apa: Krueger, A., Warsitz, E., &#38; Haeb-Umbach, R. (2011). Speech Enhancement
    With a GSC-Like Structure Employing Eigenvector-Based Transfer Function Ratios
    Estimation. <i>IEEE Transactions on Audio, Speech, and Language Processing</i>,
    <i>19</i>(1), 206–219. <a href="https://doi.org/10.1109/TASL.2010.2047324">https://doi.org/10.1109/TASL.2010.2047324</a>
  bibtex: '@article{Krueger_Warsitz_Haeb-Umbach_2011, title={Speech Enhancement With
    a GSC-Like Structure Employing Eigenvector-Based Transfer Function Ratios Estimation},
    volume={19}, DOI={<a href="https://doi.org/10.1109/TASL.2010.2047324">10.1109/TASL.2010.2047324</a>},
    number={1}, journal={IEEE Transactions on Audio, Speech, and Language Processing},
    author={Krueger, Alexander and Warsitz, Ernst and Haeb-Umbach, Reinhold}, year={2011},
    pages={206–219} }'
  chicago: 'Krueger, Alexander, Ernst Warsitz, and Reinhold Haeb-Umbach. “Speech Enhancement
    With a GSC-Like Structure Employing Eigenvector-Based Transfer Function Ratios
    Estimation.” <i>IEEE Transactions on Audio, Speech, and Language Processing</i>
    19, no. 1 (2011): 206–19. <a href="https://doi.org/10.1109/TASL.2010.2047324">https://doi.org/10.1109/TASL.2010.2047324</a>.'
  ieee: A. Krueger, E. Warsitz, and R. Haeb-Umbach, “Speech Enhancement With a GSC-Like
    Structure Employing Eigenvector-Based Transfer Function Ratios Estimation,” <i>IEEE
    Transactions on Audio, Speech, and Language Processing</i>, vol. 19, no. 1, pp.
    206–219, 2011.
  mla: Krueger, Alexander, et al. “Speech Enhancement With a GSC-Like Structure Employing
    Eigenvector-Based Transfer Function Ratios Estimation.” <i>IEEE Transactions on
    Audio, Speech, and Language Processing</i>, vol. 19, no. 1, 2011, pp. 206–19,
    doi:<a href="https://doi.org/10.1109/TASL.2010.2047324">10.1109/TASL.2010.2047324</a>.
  short: A. Krueger, E. Warsitz, R. Haeb-Umbach, IEEE Transactions on Audio, Speech,
    and Language Processing 19 (2011) 206–219.
date_created: 2019-07-12T05:29:28Z
date_updated: 2022-01-06T06:51:11Z
department:
- _id: '54'
doi: 10.1109/TASL.2010.2047324
intvolume: '        19'
issue: '1'
keyword:
- acoustical transfer function ratio
- adaptive eigenvector tracking
- array signal processing
- beamformer design
- blocking matrix
- eigenvalues and eigenfunctions
- eigenvector-based transfer function ratios estimation
- generalized sidelobe canceler
- interference reduction
- iterative methods
- power iteration method
- reduced speech distortions
- reverberant enclosure
- reverberation
- speech enhancement
- stationary noise
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://groups.uni-paderborn.de/nt/pubs/2011/KrWaHa11.pdf
oa: '1'
page: 206-219
publication: IEEE Transactions on Audio, Speech, and Language Processing
status: public
title: Speech Enhancement With a GSC-Like Structure Employing Eigenvector-Based Transfer
  Function Ratios Estimation
type: journal_article
user_id: '44006'
volume: 19
year: '2011'
...
---
_id: '9576'
abstract:
- lang: eng
  text: 'In neurosurgery, delineation of tumor boundaries during resection of brain
    tumors is of substantial relevance. During operation distinction between tumor
    and healthy tissue rely on the abilities of the surgeon based on visual and tactile
    differentiation. In this paper a high sensitivity actuator-sensor system using
    a piezoelectric bimorph is presented. Frequency shift and transfer function of
    the bimorphpsilas voltages are detected and evaluated. Sensorpsilas sensitivity
    is evaluated using two frequency controls strategies: A phase-locked loop (PLL)
    and a self-oscillating circuit. Results of measurements conducted on gel-phantoms
    are presented and discussed.'
author:
- first_name: David Oliva
  full_name: Uribe, David Oliva
  last_name: Uribe
- first_name: Ralf
  full_name: Stroop, Ralf
  last_name: Stroop
- first_name: Tobias
  full_name: Hemsel, Tobias
  id: '210'
  last_name: Hemsel
- first_name: Jörg
  full_name: Wallaschek, Jörg
  last_name: Wallaschek
citation:
  ama: 'Uribe DO, Stroop R, Hemsel T, Wallaschek J. Development of a biomedical tissue
    differentiation system using piezoelectric actuators. In: <i>Frequency Control
    Symposium, 2008 IEEE International</i>. ; 2008:91-94. doi:<a href="https://doi.org/10.1109/FREQ.2008.4622963">10.1109/FREQ.2008.4622963</a>'
  apa: Uribe, D. O., Stroop, R., Hemsel, T., &#38; Wallaschek, J. (2008). Development
    of a biomedical tissue differentiation system using piezoelectric actuators. In
    <i>Frequency Control Symposium, 2008 IEEE International</i> (pp. 91–94). <a href="https://doi.org/10.1109/FREQ.2008.4622963">https://doi.org/10.1109/FREQ.2008.4622963</a>
  bibtex: '@inproceedings{Uribe_Stroop_Hemsel_Wallaschek_2008, title={Development
    of a biomedical tissue differentiation system using piezoelectric actuators},
    DOI={<a href="https://doi.org/10.1109/FREQ.2008.4622963">10.1109/FREQ.2008.4622963</a>},
    booktitle={Frequency Control Symposium, 2008 IEEE International}, author={Uribe,
    David Oliva and Stroop, Ralf and Hemsel, Tobias and Wallaschek, Jörg}, year={2008},
    pages={91–94} }'
  chicago: Uribe, David Oliva, Ralf Stroop, Tobias Hemsel, and Jörg Wallaschek. “Development
    of a Biomedical Tissue Differentiation System Using Piezoelectric Actuators.”
    In <i>Frequency Control Symposium, 2008 IEEE International</i>, 91–94, 2008. <a
    href="https://doi.org/10.1109/FREQ.2008.4622963">https://doi.org/10.1109/FREQ.2008.4622963</a>.
  ieee: D. O. Uribe, R. Stroop, T. Hemsel, and J. Wallaschek, “Development of a biomedical
    tissue differentiation system using piezoelectric actuators,” in <i>Frequency
    Control Symposium, 2008 IEEE International</i>, 2008, pp. 91–94.
  mla: Uribe, David Oliva, et al. “Development of a Biomedical Tissue Differentiation
    System Using Piezoelectric Actuators.” <i>Frequency Control Symposium, 2008 IEEE
    International</i>, 2008, pp. 91–94, doi:<a href="https://doi.org/10.1109/FREQ.2008.4622963">10.1109/FREQ.2008.4622963</a>.
  short: 'D.O. Uribe, R. Stroop, T. Hemsel, J. Wallaschek, in: Frequency Control Symposium,
    2008 IEEE International, 2008, pp. 91–94.'
date_created: 2019-04-29T13:07:39Z
date_updated: 2022-01-06T07:04:16Z
department:
- _id: '151'
doi: 10.1109/FREQ.2008.4622963
keyword:
- biomedical measurement
- brain
- cancer
- neurophysiology
- phantoms
- phase locked loops
- piezoelectric actuators
- surgery
- tactile sensors
- transfer functions
- tumours
- PLL
- biomedical tissue differentiation system
- brain tumor resection
- frequency control
- frequency shift
- gel-phantom
- high sensitivity actuator-sensor system
- neurosurgery
- phase-locked loop
- piezoelectric actuators
- piezoelectric bimorph
- self-oscillating circuit
- sensor sensitivity
- tactile differentiation
- tactile sensor system
- transfer function
- tumor boundary
- visual differentiation
- Biomedical measurements
- Circuits
- Frequency control
- Neoplasms
- Neurosurgery
- Phase locked loops
- Piezoelectric actuators
- Surges
- Transfer functions
- Voltage
language:
- iso: eng
page: 91-94
publication: Frequency Control Symposium, 2008 IEEE International
publication_identifier:
  issn:
  - 1075-6787
quality_controlled: '1'
status: public
title: Development of a biomedical tissue differentiation system using piezoelectric
  actuators
type: conference
user_id: '55222'
year: '2008'
...
---
_id: '11935'
abstract:
- lang: eng
  text: The generalized sidelobe canceller by Griffith and Jim is a robust beamforming
    method to enhance a desired (speech) signal in the presence of stationary noise.
    Its performance depends to a high degree on the construction of the blocking matrix
    which produces noise reference signals for the subsequent adaptive interference
    canceller. Especially in reverberated environments the beamformer may suffer from
    signal leakage and reduced noise suppression. In this paper a new blocking matrix
    is proposed. It is based on a generalized eigenvalue problem whose solution provides
    an indirect estimation of the transfer functions from the source to the sensors.
    The quality of the new generalized eigenvector blocking matrix is studied in simulated
    rooms with different reverberation times and is compared to alternatives proposed
    in the literature.
author:
- first_name: Ernst
  full_name: Warsitz, Ernst
  last_name: Warsitz
- first_name: Alexander
  full_name: Krueger, Alexander
  last_name: Krueger
- first_name: Reinhold
  full_name: Haeb-Umbach, Reinhold
  id: '242'
  last_name: Haeb-Umbach
citation:
  ama: 'Warsitz E, Krueger A, Haeb-Umbach R. Speech enhancement with a new generalized
    eigenvector blocking matrix for application in a generalized sidelobe canceller.
    In: <i>IEEE International Conference on Acoustics, Speech and Signal Processing
    (ICASSP 2008)</i>. ; 2008:73-76. doi:<a href="https://doi.org/10.1109/ICASSP.2008.4517549">10.1109/ICASSP.2008.4517549</a>'
  apa: Warsitz, E., Krueger, A., &#38; Haeb-Umbach, R. (2008). Speech enhancement
    with a new generalized eigenvector blocking matrix for application in a generalized
    sidelobe canceller. In <i>IEEE International Conference on Acoustics, Speech and
    Signal Processing (ICASSP 2008)</i> (pp. 73–76). <a href="https://doi.org/10.1109/ICASSP.2008.4517549">https://doi.org/10.1109/ICASSP.2008.4517549</a>
  bibtex: '@inproceedings{Warsitz_Krueger_Haeb-Umbach_2008, title={Speech enhancement
    with a new generalized eigenvector blocking matrix for application in a generalized
    sidelobe canceller}, DOI={<a href="https://doi.org/10.1109/ICASSP.2008.4517549">10.1109/ICASSP.2008.4517549</a>},
    booktitle={IEEE International Conference on Acoustics, Speech and Signal Processing
    (ICASSP 2008)}, author={Warsitz, Ernst and Krueger, Alexander and Haeb-Umbach,
    Reinhold}, year={2008}, pages={73–76} }'
  chicago: Warsitz, Ernst, Alexander Krueger, and Reinhold Haeb-Umbach. “Speech Enhancement
    with a New Generalized Eigenvector Blocking Matrix for Application in a Generalized
    Sidelobe Canceller.” In <i>IEEE International Conference on Acoustics, Speech
    and Signal Processing (ICASSP 2008)</i>, 73–76, 2008. <a href="https://doi.org/10.1109/ICASSP.2008.4517549">https://doi.org/10.1109/ICASSP.2008.4517549</a>.
  ieee: E. Warsitz, A. Krueger, and R. Haeb-Umbach, “Speech enhancement with a new
    generalized eigenvector blocking matrix for application in a generalized sidelobe
    canceller,” in <i>IEEE International Conference on Acoustics, Speech and Signal
    Processing (ICASSP 2008)</i>, 2008, pp. 73–76.
  mla: Warsitz, Ernst, et al. “Speech Enhancement with a New Generalized Eigenvector
    Blocking Matrix for Application in a Generalized Sidelobe Canceller.” <i>IEEE
    International Conference on Acoustics, Speech and Signal Processing (ICASSP 2008)</i>,
    2008, pp. 73–76, doi:<a href="https://doi.org/10.1109/ICASSP.2008.4517549">10.1109/ICASSP.2008.4517549</a>.
  short: 'E. Warsitz, A. Krueger, R. Haeb-Umbach, in: IEEE International Conference
    on Acoustics, Speech and Signal Processing (ICASSP 2008), 2008, pp. 73–76.'
date_created: 2019-07-12T05:31:06Z
date_updated: 2022-01-06T06:51:12Z
department:
- _id: '54'
doi: 10.1109/ICASSP.2008.4517549
keyword:
- adaptive interference canceller
- adaptive signal processing
- array signal processing
- beamforming method
- eigenvalues and eigenfunctions
- generalized eigenvector blocking matrix
- generalized sidelobe canceller
- interference suppression
- matrix algebra
- noise suppression
- speech enhancement
- transfer function estimation
- transfer functions
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://groups.uni-paderborn.de/nt/pubs/2008/WaKrHa08.pdf
oa: '1'
page: 73-76
publication: IEEE International Conference on Acoustics, Speech and Signal Processing
  (ICASSP 2008)
status: public
title: Speech enhancement with a new generalized eigenvector blocking matrix for application
  in a generalized sidelobe canceller
type: conference
user_id: '44006'
year: '2008'
...
---
_id: '11927'
abstract:
- lang: eng
  text: Maximizing the output signal-to-noise ratio (SNR) of a sensor array in the
    presence of spatially colored noise leads to a generalized eigenvalue problem.
    While this approach has extensively been employed in narrowband (antenna) array
    beamforming, it is typically not used for broadband (microphone) array beamforming
    due to the uncontrolled amount of speech distortion introduced by a narrowband
    SNR criterion. In this paper, we show how the distortion of the desired signal
    can be controlled by a single-channel post-filter, resulting in a performance
    comparable to the generalized minimum variance distortionless response beamformer,
    where arbitrary transfer functions relate the source and the microphones. Results
    are given both for directional and diffuse noise. A novel gradient ascent adaptation
    algorithm is presented, and its good convergence properties are experimentally
    revealed by comparison with alternatives from the literature. A key feature of
    the proposed beamformer is that it operates blindly, i.e., it neither requires
    knowledge about the array geometry nor an explicit estimation of the transfer
    functions from source to sensors or the direction-of-arrival.
author:
- first_name: Ernst
  full_name: Warsitz, Ernst
  last_name: Warsitz
- first_name: Reinhold
  full_name: Haeb-Umbach, Reinhold
  id: '242'
  last_name: Haeb-Umbach
citation:
  ama: Warsitz E, Haeb-Umbach R. Blind Acoustic Beamforming Based on Generalized Eigenvalue
    Decomposition. <i>IEEE Transactions on Audio, Speech, and Language Processing</i>.
    2007;15(5):1529-1539. doi:<a href="https://doi.org/10.1109/TASL.2007.898454">10.1109/TASL.2007.898454</a>
  apa: Warsitz, E., &#38; Haeb-Umbach, R. (2007). Blind Acoustic Beamforming Based
    on Generalized Eigenvalue Decomposition. <i>IEEE Transactions on Audio, Speech,
    and Language Processing</i>, <i>15</i>(5), 1529–1539. <a href="https://doi.org/10.1109/TASL.2007.898454">https://doi.org/10.1109/TASL.2007.898454</a>
  bibtex: '@article{Warsitz_Haeb-Umbach_2007, title={Blind Acoustic Beamforming Based
    on Generalized Eigenvalue Decomposition}, volume={15}, DOI={<a href="https://doi.org/10.1109/TASL.2007.898454">10.1109/TASL.2007.898454</a>},
    number={5}, journal={IEEE Transactions on Audio, Speech, and Language Processing},
    author={Warsitz, Ernst and Haeb-Umbach, Reinhold}, year={2007}, pages={1529–1539}
    }'
  chicago: 'Warsitz, Ernst, and Reinhold Haeb-Umbach. “Blind Acoustic Beamforming
    Based on Generalized Eigenvalue Decomposition.” <i>IEEE Transactions on Audio,
    Speech, and Language Processing</i> 15, no. 5 (2007): 1529–39. <a href="https://doi.org/10.1109/TASL.2007.898454">https://doi.org/10.1109/TASL.2007.898454</a>.'
  ieee: E. Warsitz and R. Haeb-Umbach, “Blind Acoustic Beamforming Based on Generalized
    Eigenvalue Decomposition,” <i>IEEE Transactions on Audio, Speech, and Language
    Processing</i>, vol. 15, no. 5, pp. 1529–1539, 2007.
  mla: Warsitz, Ernst, and Reinhold Haeb-Umbach. “Blind Acoustic Beamforming Based
    on Generalized Eigenvalue Decomposition.” <i>IEEE Transactions on Audio, Speech,
    and Language Processing</i>, vol. 15, no. 5, 2007, pp. 1529–39, doi:<a href="https://doi.org/10.1109/TASL.2007.898454">10.1109/TASL.2007.898454</a>.
  short: E. Warsitz, R. Haeb-Umbach, IEEE Transactions on Audio, Speech, and Language
    Processing 15 (2007) 1529–1539.
date_created: 2019-07-12T05:30:57Z
date_updated: 2022-01-06T06:51:12Z
department:
- _id: '54'
doi: 10.1109/TASL.2007.898454
intvolume: '        15'
issue: '5'
keyword:
- acoustic signal processing
- arbitrary transfer function
- array signal processing
- blind acoustic beamforming
- direction-of-arrival
- direction-of-arrival estimation
- eigenvalues and eigenfunctions
- generalized eigenvalue decomposition
- gradient ascent adaptation algorithm
- microphone arrays
- microphones
- narrowband array beamforming
- sensor array
- single-channel post-filter
- spatially colored noise
- transfer functions
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://groups.uni-paderborn.de/nt/pubs/2007/WaHa07.pdf
oa: '1'
page: 1529-1539
publication: IEEE Transactions on Audio, Speech, and Language Processing
status: public
title: Blind Acoustic Beamforming Based on Generalized Eigenvalue Decomposition
type: journal_article
user_id: '44006'
volume: 15
year: '2007'
...