An important part of our business is to provide information so that our readers can learn more about Alternate Energy. The following list of links should keep you busy for a while.
Link Category Index
- New Additions
- publication or web resource
- newsgroup and mailing lists
- organizations and associations
- government resources
- consultants and education
- manufacturers - solar energy equipment
- manufacturers - wind energy equipment
- manufacturers - hydroelectric power equipment
- manufacturers - biomass energy equipment
- manufacturers - hydrogen and fuel cell equipment
- manufacturers - geothermal equipment
- manufacturers - Marine Energy Equipment
- manufacturers - miscellaneous energy equipment
- wholesale and distributors - solar energy equipment
- wholesale and distributors - wind energy equipment
- wholesale and distributors - other
- dealers and installers - solar energy equipment
- dealers and installers - wind energy equipment
- dealers and installers - other
- other - alternative energy vehicles
- other - personal web pages
- other - renewable energy building resources
- other - energy software and shareware
manufacturers - wind energy equipment
Aeo Energy Technology Co.,Ltd.
Based in Shanghai China,Aeo Energy has been dedicating ourself for providing the best solution in the field of renewable energy for many years. We are the professional manufacturer and supplier of the medium-small wind turbines and wind solar hybrid systems. All of our products are produced strictly according to ISO9001:2000 system code and CE certified for the European market.
Aeronautica Windpower, LLC
New Turbines to be made in the USA! Beginning in the winter of 2010 we will begin shipping our new 225 and 750 kW turbines that are now manufactured in the United States. The result will be shorter shipping times and costs in North America for American-manufactured turbines. Our 'Queen-Size' machines are larger and much more cost effective than residential-scale turbines, but smaller than the multi-megawatt 'King-Size' turbines used in large, expansive wind farms.
AHMTEC GmbH - Cable and Pipe Protection Systems
AHMTEC is a unique member of the offshore energy sector specializing in cable and pipe protection products from subsea to surface. We have developed our expertise and experience with major international organizations in the submarine cable, Oil and Gas industries and the offshore renewable energy sector, including offshore wind farms, and wave and tidal energy projects.
The mission of Airstream is to be a leader as a responsible designer, producer and provider of wind turbines from 150W to 50kW, offering wind and solar products chosen by customers for their quality, technology, performance, reliability, simplicity and lowest cost of energy, thereby accelerating global adoption of reliable and economic renewable energy providing the world a chance to make a “Small Change, Big Impact”
Ampyx Power is an Airborne Wind Energy company based in the Netherlands. Ampyx Power is a developing the PowerPlane, a machine that can extract power from the wind at significantly lower cost than wind turbines. The PowerPlane consists of a winch on the ground and an aircraft flying at about 400 meters altitude. The aircraft extracts the cable from the winch under high tension. The rotation of the drum of the winch drives a generator on the ground.
We provide conceptual and detailed designs for complete wind turbines and advanced drivetrain systems. In addition, we provide a broad range of volume manufacturing support services, including supply chain development, localization and employee training. Our offerings also include advanced wind turbine electrical control systems that ensure highly reliable and efficient power flow.
Argosy Wind Power
Argosy Wind Power is a global wind turbine leader that uses innovative technology to produce turbines with a variety of purposes. From industrial to residential, Argosy Wind Power has a turbine that is sure to suit your needs.
The recent release of 'Car Parts App' for the iPhone could pave the way for updated and innovative automotive sales
B.A.G. Corp.® manufactures Super Sack® containers, woven polypropylene flexible intermediate bulk containers (FIBCs) for shipping, handling and storing of dry, flowable products and bulk liners for boxes, drums and FIBCs.
We manufacture high accuracy anemometers and other wind and weather sensors along with robust data logger products. We also specialize in providing engineering design and consulting services.
Bergey Wind Power
Bergey Windpower is the worldĂ˘â‚¬â„˘s leading supplier of small wind turbines. With installations in all 50 States and more than 90 countries, Bergey wind turbines have proven to be the best-built and most rugged turbines available.
Crum Manufacturing has been in business for over 20 years. We are ISO-9001 certified. We are a complete machine shop with design, fabrication, milling, turning, welding, finishing, and CMM services. We are available for rapid prototyping, inspection fixtures, and mass production runs. Please contact us today and allows us to help your company!
MANUFACTURING OF SMALL WIND TURBINES
Manufacturer of small wind turbunes and wind-diesel stand alone power systems, wind projects developer
Endurance Wind Power Inc. is the producer of a complete line of small to mid-sized, grid-connected (inverterless) wind turbines. One of the only manufacturers in the world to offer a complete suite of wind turbine products that are all built to safety and performance standards of large utility-scale multi-MW turbines. Now homes, farms, schools, businesses and even municipalities can produce their own power cost-effectively, leading the way for the new generation of clean energy.
Eocycle Technologies Inc.
Eocycle manufactures a 25 kW direct-drive wind turbine using its unique Transverse Flux Permanent Magnet (TFPM) generator and an industrial regenerative drive specially adapted by Eocycle for cost-effective electricity generation. Designed to the IEC 61400-2 and AWEA standards, the EO-25/12 achieves a combination of performance, reliability and availability unparalleled in the small wind industry together with very low operating costs. For more information please go to www.eocycle.com.
Gaia-Wind is one of the world's leading small wind turbine manufacturers. We are dedicated to helping our customers discover and benefit from the outstanding performance and economic advantages offered by our small wind turbines.
Gaia-Wind Ltd is a manufacturer of world leading high performance Small Wind Turbines, servicing farms, rural properties, businesses, and community projects. The company is headquartered in Glasgow, Scotland, with appointed distributors across the UK as well as operations in Italy, France, Denmark, Ireland, and the US. In 2012 Gaia-Wind was listed as the fastest growing private company in Scotland and the eighth fastest growing in the UK. Almost 1000 Gaia-Wind turbines have been "in the ground" for a combined operational time of more than 15 million hours. That's over 1,700 years. In Denmark, 77 of our Gaia-Wind turbines have been running for more than 10 years.
GBM Limited manufactures high quality glass reinforced plastic composites, (GRP) at their base in Dumfries and Galloway in the UK. GBM Limited has a customer base servicing most areas of industry. Through developing and supplying such a diverse range of clients, the company has produced an extensive portfolio of products and is expanding into the renewables market.
GE's wind turbines prevent as much as 18.3 million tons of greenhouse gases annually, an amount roughly equal to keeping over three million cars off the road. Learn about this attractive energy solution.
Production of new design wind turbines.
Gill Instruments manufacture and supply ultrasonic anemometers and wind sensors for wind analysis. Gill 2-axis anemometers are particularly suited to wind turbine applications where operating conditions are often especially harsh.
Green Power Generator Mfg Co Ltd
Green Power Generator Mfg Co Ltd is a Sino-foreign joint venture, with its headquarters in Hong Kong and production factory in Shunde, Guangdong/China. The factory is located on a 20,000 square meter area and occupies over 200 employees, who contribute to the design and produce of small-scale wind turbines, power range from 100W to 2KW.
Greenergy Technology Co.,Ltd
we are micro and small wind turbine manufacture in China. The following is the detail of our products: 1) Micro wind turbine, from 200W to 3 KW, we supply the traditional wind turbine and vertical wind turbine both. 2)Small wind turbine from 3KW to 100KW,we supply the traditional wind turbine and vertical wind turbine both. 3)towers for these wind turbine, free stand type guy cable type, and we have a hydraulic tower system to help you install wind turbine easier. www.windgreenergy.com
Hurricane Wind Power Wind Turbine Technologies LLC
Wind Generators and Wind Power Products Made in USA by Hurricane Wind Power Wind Turbine Technologies LLC
Inerjy is an engineering, development, and manufacturing company focused on technologies for clean energy proliferation. Inerjy has developed wind energy solutions for communities, schools, industries, islands and government agencies who want to take the lead with a financially sound wind energy project.
JAKOB GRUPPE / Optima Spanntechnik GmbH
Thanks to more than 40 years of experience, Optima Spanntechnik is one of the leading manufacturers of clamping systems. International customers from all kind of industries rely on the know-how of the technicians and engineers from Scheuerfeld in Germany. By including hydraulic and electromechanical rotor-lock systems for wind turbines in its portfolio, Optima Spanntechnik is breaking new ground in this pioneering market by offering extraordinary quality and a comprehensive service.
JLM Energy Inc.
JLM Energy is an energy technology company. We are a team of engineers, entrepreneurs and customer-facing professionals dedicated to research and development of products aimed at reducing the energy expenditure of our commercial, industrial and residential customers.
Kestrel Renewable Energy
A subsidiary of Eveready, Kestrel Renewable Energy (Kestrel) is proudly South African and benefits from world-class manufacturing processes and talent. Based in the automotive hub of South Africa, Kestrel meets rigorous quality controls and safety standards recognised worldwide and are the Eastern Cape Exporters Club SME Exporter of the Year.
Low wind LLC
Low Wind Speed Turbines & Windmills
Magnetek, Inc. offers E-Force® Renewable Energy Inverters. Magnetek’s modular grid-tied E-Force Inverters turn DC power produced by photovoltaic systems into clean, utility-grade, distributed AC power. The E-Force’s proven design increases the power harvested from renewable sources, reduces the time and cost of installation and ensures a long service life. Magnetek’s 20 years of renewable energy experience assures you of the most advanced, proven power control technology available.
Mariah Power provides low-cost, easy-to-install small-scale vertical axis wind appliances to residential, commercial and government customers. The company's first product is the innovative Windspire vertical wind turbine. Featured on "20/20" and "Extreme Makeover: Home Edition" the Windspire is quiet, affordable and at only 30 feet tall it is suitable for urban, suburban and semi-remote areas. Made in Michigan, the Windspire is changing the small wind market in a big way.
MAX Nature Green Energy Limited
MAX Nature Green Energy is a manufacturer of small wind turbine 100W-200kW, supplies hydro electrical generators 300W-500kW; Provides customised solutions as project Contractor of renewable energy; Looking for distributors and dealers all the world;
MAXA ENGINEERING CO.,LTD
MAXA Engineering was established from Harda company re-organization. We are aimed at quick and creative product design on top of our experienced tool and manufacturing services. Our customers widely cover not only manufacturers but also industrial design companies. We hope our comprehensive service enables to bring maximum value to you from design, through prototyping, testing, tooling and manufacturing and eventually deliver the merchandises.(www.maxaengineering.com)
Moltec Windpower Products
Moltec offers its Modular, Plug & Play, Intertek/ETL Listed Tower & Nacelle Lighting and Electrical Systems for applications in the US and Canada. High quality design and construction assures a durible long lasting system that installs in 20% of the time required for typical "hand wired" systems, saving installers time and installtion costs. Moltec also offers its UL/CSA Listed "econolumen" light fixtures specifically designed to withstand the extremes of the wind energy environment.
Moventas is one of the largest manufacturers of wind turbine gears in the world. The company also manufactures power transmission solutions for industry use and provides services for their overhaul and maintenance. Majority of the products' end use is connected with renewable energy. In 2008 Moventas generated net sales of EUR 382 million. The company has over 1300 employees in 8 countries globally with a world-wide partner network.
Nordex USA, Inc.
With the serial produced multi-megawatt wind turbines Nordex N80, N90, N100 and N117, Nordex is able to offer high-efficiency wind turbines for onshore use.
NRG Systems is an independently owned company that has served the global renewable energy industry for nearly 30 years. Electric utilities, wind farm developers, turbine manufacturers, research institutes and universities on every continent and in more than 145 countries rely on the company's resource assessment systems, turbine control sensors, and lidar remote sensors. For more information, visit www.nrgsystems.com.
Obsta - Obstruction Lighting
OBSTA manufactures reliable Obstacle Warning Lights for Air Traffic.These lights are available with High, Medium and Low intensity levels in accordance with FAA (L-856,L-864,L-810) & ICAO standards. OBSTA has pioneered the use of COLD NEON and XENON technologies for fixed and flashing light applications and designed new energy efficient LED lights.
Permanent Magnet Generators Ltd. (PMGL)
PM Generators Ltd. (PMGL) is a leading manufacturer of ISO certified Permanent Magnet Generators and Control Systems. With its international contracts, the company deals with envronment-friendly hybrid generators (wind, hydro) throughout USA, Europe, Africa, and Asia.
Power-One manufacturers the Aurora family of residential and commercial inverters for wind and solar applications. These products are high efficiency and installer friendly.
PowerWind GmbH is a German manufacturer of wind turbines with 850 kW, 900 kW und 2500 kW rated power as well as a provider of product-specific services. The company was founded in 2007 and is financed by the international investor Warburg Pincus. PowerWind is represented in Germany at two locations, Hamburg and Bremerhaven. The 900 kW PowerWind 56 wind turbine has been in series production since 2008. The first 2.5 MW wind turbine of the type PowerWind 90 has been installed by the end of 2010.
ReDriven Power Inc.
ReDriven Power Inc is a producer of 3kW, 5kW, 10kW, 20kW and 50kW wind turbine systems. These very reliable active yaw systems are well suited for on grid use. ReDriven turbines are ideal for use by farms, cottages, ranches, rural homes, schools and small industrial businesses. Characterized by energy production at very low wind speeds, the ReDriven wind turbines will deliver higher output as at higher wind speeds the turbine will turn out of the wind while producing maximum power.
The UK's third largest supplier of wind turbines
Rock Wind, LLC
Rock Wind, LLC developed methods to cost-effectively remanufacture decommissioned turbines. Selling them at a substantially lower cost than new equivalents. We utilize the newest technologically advanced procedures, unavailable at the time of original manufacturing. After complete disassembly, all components (computer,generator,gearbox, braking system) are inspected and either replaced or refurbished. All exterior components sandblasted and repainted, then reassembled for on-site delivery.
The Roxtec system simplifies design and engineering for cable entry systems. It speeds up the installation process and reduces the need for stock, material, and logistics. It also provides built-in spare capacity for easy retrofit and future upgrades. We are quickly becoming the standard in the industry due to the flexibility of Multidiameter™. The result of our system is a perfect seal that keeps your equipment and environment protected and operating efficiently.
Schaeffler UK Ltd
The Schaeffler Group is a leading manufacturer of high precision rolling bearings, linear bearings and automotive components for engine, transmission and chassis applications. Sales of more than 9.5 billion euros were generated at over 180 locations in more than 50 countries in 2010. Schaeffler bearings and condition monitoring systems are helping to ensure the efficiency and safety of many wind farms, as well as tidal, wave and solar energy installations around the world.
Seab Energy Ltd
SEaB Energy Ltd is an innovative designer and manufacturer of Distributed Microgeneration Systems based in Hampshire, United Kingdom. We manufacture two products: Windbuster™, a 5kW vertical axis wind turbine, and Muckbuster™, a small anaerobic digester (1/2 tonne/day processing capacity). Our products are sold directly and through local resellers.
Second Wind's advanced tower-based and remote sensing (sodar) wind measurement technology is used in over 50 countries by wind farm owners, developers, and consultants to understand and improve the financial performance of wind projects.
senwei energy technology co.,ltd
SENWEI ENERGY TECHNOLOGIES INC set up in 1996, is one of the leading manufactories of small wind turbine generators in China. We specially manufacture 300W to 50KW wind turbine generators, grid tie inverter,small wind turbines/solar hybrid system, solar power,hydraulic tower, fixed pitch wind turbine, variable pitch wind turbine, grid off system ,grid on system for the world market.
Shanghai Ghrepower Green Energy Co., Ltd.
GHREPOWER is a leading wind turbines manufacturer which specializes in R&D and manufacture in china. We have integrated design, production, installation, commissioning, sale and after-sale service, and out products are widely applied for mobile communication, millitary, maritioe monitor, home use, commercial business and remote area etc. The company's current wind turbine portfolio includes 300W, 500W, 2kW, 5kW, 10kW, 30kW, 50kW and 100kW, together with the controller, inverter, tower etcs
Our Energy Sector is one of the world’s leading suppliers of a wide range of products, solutions and services in the field of energy technology. We enable customers to generate, transmit and distribute electrical power at the highest levels of efficiency. We also help them produce, convert and transport the primary fuels oil and gas. We’re the only manufacturer worldwide with know-how, products, solutions and key components spanning the entire energy conversion chain.
Hardy solar pioneer in alternative energy since 1977 is now specializing in the sky stream product line
The world's leading manufacturer of battery charging wind turbines for remote homes, sailboats, recreational vehicles, telecommunications, and hybrid systems offers a complete line of wind turbines for virtually any application.
Southwest Windpower has been designing and distributing small wind turbines for more than 22 years and is the recognized global leader in the design, manufacturing and distribution of small wind systems (400-3000 watts). The company has been a pioneer in the development of wind technology and has built and shipped more than 160,000 wind turbines to over 120 countries worldwide and has sales representation in over 88 countries. Headquartered in Flagstaff Arizona.
Springfield Energy Systems
Alternitive Energy Developer
Based in California, Stanford Magnets has been involved in the R&D and sales of licensed Rare-earth permanent magnets, Neodymium magnets and SmCo magnets alike to support fully a wide variety of commercial wind turbines, in efforts to ensure high energy-efficiency for the whole generator systems.
Specializing in Alternate Energy Systems for: > Homes > Cabins and Cottages > Hunting Lodges > Remote Power > Emergency Lighting > Backup Power > Ham and CB Radio Power > Cell Phone Charging > Farms And Many Many Other Uses American made, rugged, Do-It-Yourself friendly, with the latest high-tech components. VERY affordable. Easily mounted on common 1.5 inch water pipe, or a tower. Rated at 400 watts per head at 28 mph and much, much more in higher winds.
Suzhou Newmeil Machinery And Equipment Corp
We are Suzhou Newmeil Wind Turbine company, a professinal small wind turbine provider with over 10 years of experience in the industry. We specialize in designing smart wind turbines system of from 400W-5Kw , at the moment, our main line of products include: V400 wind turbine; X600 wind turbine; X2000 wind turbine. for more details, pls visit our web: www.newmeilwindturbine.com
Talk, Incorporated specializes in the re-manufacturing of Danish made wind turbines from 65 to 225 KW. We are also introducing a new 100 KW turbine in 2011 that will be focused on dispersed wind installations for farms, schools and light industry. We provide services from turbine supply, installation, commissioning and provide O&M services. Strategically located in west central Minnesota we are able to efficiently reach many key wind zones in the upper midwest.
Tentec offer purpose designed bolt tensioning tools and hydraulic torque wrenches for wind turbines. Developed over many years, our wind turbine bolt tightening solutions offer the most advanced, safe, rapid and operator friendly tools in the market today.
The Switch was one of the first wind power companies that pioneered permanent magnet generator (PMG) and full-power converter (FPC) solutions, making them commercially available. The Switch Drive™ is a fully optimized generator and converter package, available in the widest range of packages to maximize wind power generation. Recently launched, The Sun Switch is a utility-grade solar inverter with a rugged outdoor design and totally self-contained liquid-cooling system with proven LVRT ability.
Tir Market Ltd
Tir Market Ltd is a leading company for manufacture of plastic parts and details. We offer complex services and products, which are providing a wide range of industrial enterprises in Power industry, Large-scale mining industry, Chemical, Railway industry, Engineering, Shipbuilding and Ship repair industry. Since 2006 we represent the products of the copmany "QUADRANT" Belgium and from 2009 we are official representatives of the company "NYLACAST". TIR MARKET LTD. obtains ISO 9001:2008 a Quality Management Standard and ISO 14001:2004 an Environmental Management Standard. The materials we manufacture have been approved by adequate Certificates of Quality as well as by Lloyd's Register Quality Assurance for the Shipbuilding and Ship repair industry.
TRENDELKAMP - Wind Energy L.P.
TRENDELKAMP L.P., (located just 10 miles north of Atlanta, GA) is a very well known manufacturer of a variety of Maintenance Lifts and Blade Access Systems for wind-towers and all wind- and renewable energy facilities. For over 40 years TRENDELKAMP provides excellent engineering and quality manufacturing work on projects worldwide. www.trendelkamp.com/english/special_constructions/maintenance-lifts/index.php
UPSAPS.com - technoWIND
First online green space in Lebanon And the Middle East, from north America to China and cross Lebanon And the middle east our scientists and engineers are ready to help you finding your power needs economically and ecologically
Urban Green Energy
Urban Green Energy (UGE) is a global leader in small wind energy and renewable energy systems. With over 100 distributors and installations in nearly 50 countries, UGE designs, manufactures, and markets cutting-edge vertical axis wind turbines as well as hybrid wind/solar streetlamps with a track record of high performance, safety, and reliability. Please visit www.urbangreenenergy.com to learn more about how Urban Green Energy can help you live a more sustainable life.
UrWind Inc. is an innovative North American company dedicated to designing and manufacturing urban wind turbines that are easily installed on both towers and rooftops permitting homeowners, businesses, and institutions to produce clean renewable energy and take control of their energy bills. UrWind offers a powerful, quiet, and affordable vertical axis wind turbine that will easily blend in urban and suburban settings, while sending a a strong environmental message.
Vaigunth Ener Tek (P) Ltd
We are manufacturing Small wind Turbine range from 200 Watts to 5-Kw. Our Turbines are having more swept area than other Small Wind turbines, That gives you more power production even low wind velocity (Less than 10 m/s).
Vos Prodect Cable & Pipe Protection
Manufacturers of cable & pipe protection equipment for the wind, wave, tidal, oil & gas and water industries.
Compact (1M to 0.5M), Light Weight (<20k), Fully Modular & Customizable VAWT witn an estimated 5000k/W year output Product Highlights/Unique Features: * 4 independent turbines and 16 generators operating in tandem within a very compact space, each generator with potential to produce output of a turbine of similar size currently available in the market * It was possible to incorporate such a high number of generators due to our new & unique generator design. The standard turbine generator has both the magnets and copper coil wire contained within the same vessel and utilize a crankshaft to transform motion to energy. In our own design, magnets and copper coil wire are contained within two separate vessels (hallow subservient rings) and turbine blades are directly placed in between one pair of such rings and therefore able to operate without a crank shaft and addociated loss of efficiency
Wind and Weather
This site gives the information on Wind and Weather which provides weather, Home and Garden products like weather instruments, weather stations, barometers, hygrometers, rain instruments, wind instruments, thermometers, yard, garden, accessories.
Wind Energy Update
Wind Energy Update is the reference point for any business and over 35,000 senior executives who work in wind energy power generation. We specialise in the construction, installation and power generation of offshore wind farms, offering an impartial view on what's happening and why. Fundamental to our business are the forums we organise. Taking place worldwide the events explore industry opportunities, challenges and emerging best practices. As an impartial 3rd party we tailor our off
Wind Simplicity™ is the designer, manufacturer and turn-key installer of the high-efficiency, compact, noise-free (negligible noise/vibration) Windancer™ that helps save the environment by turning pollution-free wind energy into free electricity. A portable horizontal-axis small wind turbine, with a sustainable life cycle, the Windancer™ (3 kW and 7 kW) is ideal for generating electricity onsite where there are good wind resources.
Wind Turbine Industries
Manufacturer of the Jacobs line of wind machines (10 kw to 20 kw).
Anemometer manufacturer. Precision wind and weather meteorological instruments for professional and residential use in wind energy.
Windjammer Energy Systems, Inc.
Specialists in diversified power platforms which include Wind Turbine generators, high capacity electricity storage, distribution, infrastructure, grid systems and retrofitting and expansion of small local area electricity service networks.
WindSL is a leading provider of vibration Condition Monitoring Systems (CMS) solutions for wind turbines. Our WT-HUMS™ (Wind Turbine Health & Usage Monitoring System), together with our proprietary RHMC™ (Remote Health Management Center) software provide real-time, automatic and accurate diagnostics and prognostics for the mechanical components of wind turbines (such as gear boxes, bearings and shafts) contributing to their overall performance.
Windspire Energy (formerly Mariah Power) designs and markets Windspire vertical axis wind turbines for use in urban, suburban, and rural areas. Windspire turbines operate silently and stand just thirty-feet tall. The unique design of the rotor provides a highly scalable solution to help businesses, schools, and homeowners meet their energy needs. The Windspire has been featured on “20/20”, CNN and NPR. For more information, visit www.windspireenergy.com.
Windstream Power Systems Incorporated
Manufacturer and distributor of wind and microhydro turbines up to 100kW, low rpm permanent magnet generators and alternators, human power generators, and independent power systems for telecom and remote sites.
Windy Nation Inc.
WindyNation designs and manufactures high-quality, precision-engineered products for use in wind turbines and solar generators. Our components and expertise bring out the best of the systems they go into!
xinda green energy co.,limited
Xinda Green Energy specialized in supply of wind turbine generator, various kind of energy saving permanent magnet generator,speed from 20rpm-6000rpm,power from 1kw to 3000kw, small hydro turbine system, wind solar hybrid system, electric motors, street lamp and so on in global market.
XZERES Wind is now designing, developing and marketing the ARE wind turbines and capitalizing on the successful brand name of ARE and its proven, small wind turbine systems.