ATE208944T1 - Globaler beruhigungsanordnung für stationäre induktionsgeräte - Google Patents

Globaler beruhigungsanordnung für stationäre induktionsgeräte

Info

Publication number
ATE208944T1
ATE208944T1 AT94926620T AT94926620T ATE208944T1 AT E208944 T1 ATE208944 T1 AT E208944T1 AT 94926620 T AT94926620 T AT 94926620T AT 94926620 T AT94926620 T AT 94926620T AT E208944 T1 ATE208944 T1 AT E208944T1
Authority
AT
Austria
Prior art keywords
global
stationary induction
calming
arrangement
induction devices
Prior art date
Application number
AT94926620T
Other languages
English (en)
Inventor
Stephen Hildebrand
Ziqiang Hu
Original Assignee
Nct Group Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Nct Group Inc filed Critical Nct Group Inc
Application granted granted Critical
Publication of ATE208944T1 publication Critical patent/ATE208944T1/de

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F27/00—Details of transformers or inductances, in general
    • H01F27/33—Arrangements for noise damping
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
    • G10K11/178—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase
    • G10K11/1785—Methods, e.g. algorithms; Devices
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
    • G10K11/178—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase
    • G10K11/1785—Methods, e.g. algorithms; Devices
    • G10K11/17855—Methods, e.g. algorithms; Devices for improving speed or power requirements
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
    • G10K11/178—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase
    • G10K11/1785—Methods, e.g. algorithms; Devices
    • G10K11/17857—Geometric disposition, e.g. placement of microphones
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
    • G10K11/178—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase
    • G10K11/1787—General system configurations
    • G10K11/17879—General system configurations using both a reference signal and an error signal
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
    • G10K2210/10—Applications
    • G10K2210/106—Boxes, i.e. active box covering a noise source; Enclosures
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
    • G10K2210/10—Applications
    • G10K2210/108—Communication systems, e.g. where useful sound is kept and noise is cancelled
    • G10K2210/1082—Microphones, e.g. systems using "virtual" microphones
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
    • G10K2210/10—Applications
    • G10K2210/119—Radiation control, e.g. control of sound radiated by vibrating structures
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
    • G10K2210/10—Applications
    • G10K2210/125—Transformers
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
    • G10K2210/10—Applications
    • G10K2210/129—Vibration, e.g. instead of, or in addition to, acoustic noise
    • G10K2210/1291—Anti-Vibration-Control, e.g. reducing vibrations in panels or beams
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
    • G10K2210/30—Means
    • G10K2210/301—Computational
    • G10K2210/3016—Control strategies, e.g. energy minimization or intensity measurements
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
    • G10K2210/30—Means
    • G10K2210/301—Computational
    • G10K2210/3027—Feedforward
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
    • G10K2210/30—Means
    • G10K2210/301—Computational
    • G10K2210/3036—Modes, e.g. vibrational or spatial modes
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
    • G10K2210/30—Means
    • G10K2210/301—Computational
    • G10K2210/3042—Parallel processing
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
    • G10K2210/30—Means
    • G10K2210/301—Computational
    • G10K2210/3046—Multiple acoustic inputs, multiple acoustic outputs
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
    • G10K2210/30—Means
    • G10K2210/321—Physical
    • G10K2210/3212—Actuator details, e.g. composition or microstructure
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
    • G10K2210/30—Means
    • G10K2210/321—Physical
    • G10K2210/3214—Architectures, e.g. special constructional features or arrangements of features
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
    • G10K2210/30—Means
    • G10K2210/321—Physical
    • G10K2210/3216—Cancellation means disposed in the vicinity of the source
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
    • G10K2210/30—Means
    • G10K2210/321—Physical
    • G10K2210/3219—Geometry of the configuration
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
    • G10K2210/30—Means
    • G10K2210/321—Physical
    • G10K2210/3229—Transducers
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
    • G10K2210/30—Means
    • G10K2210/321—Physical
    • G10K2210/3229—Transducers
    • G10K2210/32291—Plates or thin films, e.g. PVDF
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
    • G10K2210/50—Miscellaneous
    • G10K2210/501—Acceleration, e.g. for accelerometers

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Multimedia (AREA)
  • Power Engineering (AREA)
  • Soundproofing, Sound Blocking, And Sound Damping (AREA)
  • Magnetic Resonance Imaging Apparatus (AREA)
  • Regulation Of General Use Transformers (AREA)
  • Casings For Electric Apparatus (AREA)
  • Building Environments (AREA)
AT94926620T 1993-09-09 1994-09-02 Globaler beruhigungsanordnung für stationäre induktionsgeräte ATE208944T1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US11883993A 1993-09-09 1993-09-09
PCT/US1994/009712 WO1995007530A1 (en) 1993-09-09 1994-09-02 Global quieting system for stationary induction apparatus

Publications (1)

Publication Number Publication Date
ATE208944T1 true ATE208944T1 (de) 2001-11-15

Family

ID=22381036

Family Applications (1)

Application Number Title Priority Date Filing Date
AT94926620T ATE208944T1 (de) 1993-09-09 1994-09-02 Globaler beruhigungsanordnung für stationäre induktionsgeräte

Country Status (7)

Country Link
US (1) US5617479A (de)
EP (1) EP0746843B1 (de)
JP (1) JP3031635B2 (de)
AT (1) ATE208944T1 (de)
CA (1) CA2169967C (de)
DE (1) DE69429111T2 (de)
WO (1) WO1995007530A1 (de)

Families Citing this family (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5732143A (en) 1992-10-29 1998-03-24 Andrea Electronics Corp. Noise cancellation apparatus
WO1996011466A1 (en) * 1994-10-06 1996-04-18 Duke University Feedback acoustic energy dissipating device with compensator
US5754662A (en) * 1994-11-30 1998-05-19 Lord Corporation Frequency-focused actuators for active vibrational energy control systems
US6363345B1 (en) 1999-02-18 2002-03-26 Andrea Electronics Corporation System, method and apparatus for cancelling noise
US6594367B1 (en) 1999-10-25 2003-07-15 Andrea Electronics Corporation Super directional beamforming design and implementation
SE0100334L (sv) * 2001-02-05 2002-08-06 Abb Technology Ag En anordning och en metod för aktiv akustisk dämpning och användningen därav
CA2440926C (en) * 2002-09-20 2012-10-30 Isao Kakuhari Noise control apparatus
TW200826062A (en) * 2008-01-15 2008-06-16 Asia Vital Components Co Ltd System of inhibiting broadband noise of communication equipment room
JP5227263B2 (ja) * 2008-06-03 2013-07-03 パナソニック株式会社 能動騒音低減装置及びシステム
US8331577B2 (en) * 2008-07-03 2012-12-11 Hewlett-Packard Development Company, L.P. Electronic device having active noise control with an external sensor
DE102008061552A1 (de) * 2008-12-11 2010-07-01 Areva Energietechnik Gmbh Verfahren und Vorrichtung zur Geräuschminderung für einen elektrischen Transformator
US9020156B2 (en) 2009-07-24 2015-04-28 Siemens Aktiengesellschaft Method for reducing the noise emission of a transformer
JP6423688B2 (ja) * 2014-11-06 2018-11-14 株式会社日立製作所 静止誘導電器
JP6631030B2 (ja) * 2015-04-23 2020-01-15 富士電機株式会社 静止誘導電器
ES2915268T3 (es) 2015-06-06 2022-06-21 Yehuda Oppenheimer Un sistema y método para la reducción activa de un ruido acústico de audio predefinido mediante la utilización de señales de sincronización
US9646761B2 (en) * 2015-07-28 2017-05-09 Fortune Electric Co., Ltd. Power transmission transformer with a noise inhibiting function
CN105261354B (zh) * 2015-09-09 2019-10-15 东南大学 一种有源降噪自适应主动噪声控制系统及其控制方法
TR2021019429A2 (tr) * 2021-12-08 2021-12-21 Detsa Trafo Kazan Imalati Ve Celik Konstrueksiyon Sanayi Ticaret Anonim Sirketi Akti̇f ses ve ti̇treşi̇m azaltici bi̇r si̇stem

Family Cites Families (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2776020A (en) * 1955-02-09 1957-01-01 Gen Electric Noise reducing system for transformers
FR1494967A (fr) * 1966-08-04 1967-09-15 Centre Nat Rech Scient Procédé électroacoustique d'absorption des sons et bruits gênants dans des zonesétendues
US4025724A (en) * 1975-08-12 1977-05-24 Westinghouse Electric Corporation Noise cancellation apparatus
JPS5717027A (en) * 1980-07-03 1982-01-28 Hitachi Ltd Vibration reducing device of electric machinery
JPS5827313A (ja) * 1981-08-11 1983-02-18 Hitachi Ltd 静止誘導電器の振動低減方法
JPS5895806A (ja) * 1981-12-02 1983-06-07 Hitachi Ltd 静止誘導電器の防音装置
JPS58143510A (ja) * 1982-02-20 1983-08-26 Hitachi Ltd 静止誘導電器
US5020978A (en) * 1989-11-30 1991-06-04 Nashif Ahid D Apparatus and method for reducing vehicular fuel pump noise
US5091953A (en) * 1990-02-13 1992-02-25 University Of Maryland At College Park Repetitive phenomena cancellation arrangement with multiple sensors and actuators
US5315661A (en) * 1992-08-12 1994-05-24 Noise Cancellation Technologies, Inc. Active high transmission loss panel

Also Published As

Publication number Publication date
CA2169967C (en) 2000-04-11
JP3031635B2 (ja) 2000-04-10
DE69429111D1 (de) 2001-12-20
US5617479A (en) 1997-04-01
WO1995007530A1 (en) 1995-03-16
JPH08511634A (ja) 1996-12-03
EP0746843B1 (de) 2001-11-14
EP0746843A4 (de) 1998-12-09
CA2169967A1 (en) 1995-03-16
EP0746843A1 (de) 1996-12-11
DE69429111T2 (de) 2002-07-11

Similar Documents

Publication Publication Date Title
ATE208944T1 (de) Globaler beruhigungsanordnung für stationäre induktionsgeräte
ATE209078T1 (de) Werkstückaufspanntisch
ES2178033T3 (es) Procedimiento y disposicion para el control de la propagacion de campos magneticos a traves de convertidores electrodinamicos/electromagneticos, especialmente en aparatos de telecomunicacion.
ATE138166T1 (de) Führung eines objekts auf einem schienentisch mittels einer gruppe von rollenden schienenlaufelementen
DE59205082D1 (de) Gesteuerter motor
ES437365A1 (es) Maquina dinamoelectrica trifasica.
MX9604290A (es) Recinto para dispositivo electronico externo resistente a la intemperie.
ATE22660T1 (de) Magnetotherapeutische impulseinrichtung.
ATE219869T1 (de) Statorplatte eines linearen elektrischen direktantriebes
JPS53106539A (en) Electronic desk calculator with audio
DK0584660T3 (da) Fremgangsmåde og kredsløbsindretning til reduktion af oversvingninger
ATE358263T1 (de) Schutzbezug für schweissvorrichtungen
Gupta et al. Experimental investigation of sound-absorbing material of different surface shapes on noise reduction performance of an acoustic enclosure
ITMI930768V0 (it) Custodia per cavi passanti particolarmente per il montaggio su armadi per quadri elettici
JPS5316503A (en) Light transmission unit
GB1154016A (en) A Transformer Tank having a Sound-Absorbing and Sound-Damping Wall
SE9704480L (sv) Strömövertonsdämpningsanordning i en motor
JPS52104738A (en) Protecter (protective equipment) of electric source and load
CA2343903A1 (en) Controlling operation of an ac/dc converter
ES8602333A1 (es) Control electronico para equipos con videodisco
JPS54157240A (en) Interior electrical equipment control device
JPS54124240A (en) Apparatus for fitting devices in switchboard
AT369909B (de) Als integrierter schaltkreis aufgebaute einrichtung zur steuerung eines loesch- und vormagnetisierungs-stromquellengenerators
JPS5780297A (en) Set ring system for pulse motor
JPS5391355A (en) Power distribution unit

Legal Events

Date Code Title Description
RER Ceased as to paragraph 5 lit. 3 law introducing patent treaties