Electrical Engineering for Buildings, Wireless Telecom sites, Solar Energy, EV Chargers, Data Centers, Crypto-Mining, Hospitals and Infrastructure. Serving clients though out the USA + International jobs. NOW OFFERING FULL MEP/FP ENGINEERING IN CA, FL, LA, MD, OR, PR, TX! Owner of Rivera Engineering LLC, a state of the art EE firm based in the cloud, with US and global reach. José enjoys leading, and collaborating with his top notch international staff. :-) He is a full time Top 1% Rated Plus consultant that really can take care of your job! Not a drained moonlighter... Fully backed up by a $2,000,000 professional liability (E&O) insurance. See our Upwork reviews and success rate! A leader in Power Engineering for Wireless Telecom sites, Solar Energy and EV Chargers. Has delivered thousands of projects, and calculations for all the major cellular phone carriers in the US (AT&T, Sprint, T-Mobile, Verizon). And many project reviews (and stamps) for Solar and EV Chargers installers nationwide. PE licensed in: AL, AZ, CA, CO, CT, DC, DE, FL, GA, HI, ID, LA, IL, KS, LA, MA, MD, MI, MN, MO, MS, NC, NJ, NM, NV, NY, OK, OR, PA, TN, TX, UT, VA, WA. And adding more as needed. :-) Offers Electrical Engineering supervision (Review and Stamp) for Permit and Construction packages; Buildings, Solar Energy, Telecommunication sites and Infrastructure. MEP team building and leadership. José has evaluated and analyzed electrical building systems. He has provided expert (forensic) opinions related to the cause and extent of damage and prepared recommended remedial actions for property owners, municipalities, insurance carriers, and attorneys. José's project experience includes commercial and residential facilities that have been subject to damage related to installation, construction, design defects, fires and hurricanes. José has performed engineering evaluations following historical events such as Hurricane Harvey and Hurricane Michael. He is an avid enthusiast of energy-efficiency design practices with focus on renewable energy. And a sought out expert IECC-Title 24 practitioner. Has performed many technical reviews of construction documents, building and site surveys, inspections, electrical infrastructure evaluations and systems (LEED) commissioning. Breadth of project experience in city infrastructure, High and Medium Voltage substations, correctional, municipal, aviation, education, healthcare, commercial, industrial and residential facilities. Had the adventure of working in Saudi Arabia; as an advocate to the Kingdom during construction and commissioning of electrical industrial infrastructure. He has a successful career based on work ethics, integrity, team-work and reliability. Computer literate with strong AutoCAD knowledge. And plenty of experience with EE analysis and MS productivity software. Bilingual, English and Spanish. SERVICES Electrical Engineering / AutoCAD / Title 24 / IECC / Fault Calcs / Arc Flash / One line / NEC loads Systems Commissioning / Electronic Security / Forensics / Assessments / EE for Crypto Mining 3rd party Inspections / Engineering Studies / Disaster Recovery / FEMA subcontracting Lighting Design / LEED Certification support / Electrical Testing / Predominant Use Alternative Energy Consulting; Solar and Wind / Power Engineering for Telecom / EE for EV Chargers PE licensed in: Alabama, Arizona, California, Colorado, District of Columbia, Delaware, Florida, Georgia, Hawaii, Idaho, Illinois, Kansas, Louisiana, Maryland, Massachusetts, Michigan, Missouri, Mississippi, New Jersey, North Carolina, Nevada, New Mexico, Nevada, New York, Oklahoma, Oregon, Pennsylvania, Tennessee, Texas, Utah, Virginia, Washington. See more info at: www|riveramep|com

I'm Paul and I have 7 years of experience in PCB design, prototyping, and firmware development for IoT applications, robotics, and embedded systems... in addition to being a team leader for many startup projects. Quality and schedule are two criteria I always commit to with my clients so I look forward to hearing from you so we can discuss more the job as well as have the opportunity to cooperate with you for a long time. 1. WORK EXPERIENCE - Multi-layer PCB design experience with: • Microprocessor circuit: ARM Cortex-M3, Cortex-M4, Cortex-M7, AVR, PIC, ATSAM3x8E (Arduino Due), ATMega2560 (Arduino Mega), nRF52840, nRF5340, etc. • SoM, SoC: CM4, Rasp, iMX8, Jetson Nano/Xavier/Orin, RK3588 Rockchip, AM625,... • High-speed: USB 2.0, HDMI 2.0, DDR3/DDR4, PCIe, NAND Flash, Ethernet 10/100/1000base-T1, etc. • Power supply: DC-DC (isolated, Flyback, Boost, Buck, LDOs…). • Communication circuit with motor driver: BLDC, AC servo, DC servo…via I/O, ADC and CAN. • Analog signal processing circuit: ADC, DAC, Audio. • Protocol/communication: o QSPI, I2C, RS485, RS232, CAN, Modbus TCP/IP, RTU, etc. o Wireless, IoT: RF, Wifi, Bluetooth 4.0, GSM (3G, 4G/LTE), Lora... - Experience in building evaluation kits such as Arduino, ESP32, ESP8266, STM32... - Combine dimensional drawings on paper and actual PCBs to be performed into Gerber format with very high similarity. - BOM creation from favorite suppliers: Digikey/Mouser/JLCPCB, LCSC... - Experience in the field of robotics research and development: Automated Guided Vehicles (AGV), AMR, vending machines, 6-axis robots... 2. MAIN SKILLS: - Routing: Clock signals, Differential pair, Bus & single-ended traces with noise consideration… - Knowledge of proper layout techniques for EMC and EMI compliance. - Knowledge of DFA, DFM, and PCB manufacturing and assembly processes. - Good reading and understanding of datasheets, schematics. - Good knowledge of electronics component theory and application 3. OTHER SKILLS - Manage the design, fabrication, and procurement processes to acquire the PCBs in a timely and cost-efficient manner. - Initiative, team working, research, and problem-solving skills are pretty good. - Excellent electrical evaluation, testing, and PCB troubleshooting skills. - Firmware development using C, C++, and Python language, QT... - IoT: MQTT, Thingsboard, AWS, Google IoT... 4. TOOLS and SOFTWARE - Experience with Schematic Capture and Layout with Altium Designer version 18.x, 21.x, and KiCAD Ver6.x7.x, Eagle 9.6.2, EasyEDA, Altium365/CircuitMarker. - Understanding of simulation tools such as OrCAD Capture and PSpice. - Checking the Gerber with CAM350 version 12.1 - Basic use of support tools such as AutoCAD, Autodesk Inventor…

𝚃𝙾𝙿- 𝚁𝚊𝚝𝚎𝚍 𝙵𝚛𝚎𝚎𝚕𝚊𝚗𝚌𝚎𝚛 🚀, 𝙹𝙾𝙱 𝚂𝚞𝚌𝚌𝚎𝚜𝚜 > 90 % , 𝚃𝙾𝙿 1% 𝙲𝚘𝚖𝚙𝚞𝚝𝚎𝚛 𝚅𝚒𝚜𝚒𝚘𝚗, 𝙿𝚢𝚝𝚑𝚘𝚗, 𝙼𝙰𝚃𝙻𝙰𝙱 𝙵𝚛𝚎𝚎𝚕𝚊𝚗𝚌𝚎𝚛𝚜 Multidisciplinary Engineer | 🚀 5 Years studying Physics, Computer Science, Statistics, Mechanical Engineering, Electrical engineering, Problem Solving .| 🟢👁️‍🗨️ 𝓒𝓸𝓶𝓹𝓾𝓽𝓮𝓻 𝓥𝓲𝓼𝓲𝓸𝓷 𝓢𝓴𝓲𝓵𝓵𝓼 ㅤ Image Processing ㅤ |󠀠󠀠 ㅤ Yolov5 , Yolov7, YOlOv8 ㅤ | ㅤ Object Detection ㅤ | ㅤ Image Classification ㅤ | Feature Extraction ㅤ | ㅤ Deep Learning for Vision ㅤ | ㅤ OpenCV Proficiency ㅤ | ㅤ Convolutional Neural Networks (CNNs) ㅤ | ㅤ Image Segmentation ㅤ | ㅤ Facial Recognition ㅤ | Optical Character Recognition (OCR) 🔵🧠 𝓜𝓐𝓣𝓛𝓐𝓑 𝓢𝓴𝓲𝓵𝓵𝓼 : 4 years in MATLAB programming ㅤ | ㅤ Signal Processing Toolbox ㅤ | ㅤ Image Processing Toolbox ㅤ | ㅤ Machine Learning ㅤ | Simulink for modeling | ㅤ Simulink Control Design ㅤ | ㅤ Statistics and Machine Learning Toolbox ㅤ | ㅤ Optimization Toolbox ㅤ | ㅤ MATLAB App Designer | Robotics Toolbox | ㅤ Financial Toolbox | ㅤ Global Optimization Toolbox 🟡🐍 𝓟𝔂𝓽𝓱𝓸𝓷 𝓢𝓴𝓲𝓵𝓵𝓼: 5 years in Python programming ㅤ | NumPy | SciPy | ㅤ Pandas ㅤ | Matplotlib ㅤ | ㅤ Seaborn ㅤ | ㅤ Scikit-learn ㅤ | ㅤ OpenCV ㅤ | ㅤ TensorFlow PyTorch ㅤ | ㅤ Keras | ㅤ Jupyter Notebooks | ㅤ TensorFlow ㅤ | ㅤ Pytest ㅤ | ㅤ Docker | ㅤ NumPy and SciPy ㅤ | SQLAlcheme

Welcome to my profile. Following are my key expertise: 1. Over 10 years of experience in electronics circuit design, PCB design, Layout specializing in analog, digital and mixed signal systems. Special Mastery in ALTIUM. Executed more than 500 projects 2. Proficient in using industry-standard design tools such as Altium Designer, EAGLE, KICAD, EASYEDA and PROTEUS, ensuring accurate and efficient circuit development. 3. IPC Certified Symbols and footprints Creation, High Speed PCB Design upto 5GHz 4. Multilayer PCB Design experience upto 32 Layers, Impedance Control, Length Matching, Antenna Tuning, Blind Vias, Buried Vias, Through Hole Vias 5. DFX(Design for Excellence) - DFA, DFM and DFT. First Time Right PCB - 98% 6. Compact PCB Design, Signal Integrity, Power Integrity, Single Sided, Double sided placement 7. Design Verification through Design Checklists ensuring robust, reliable and quality design 8. Applications- IOT, Consumer, Medical, Industrial, Defense etc 9. Microcontroller Interfacing - STM32, STM8S, ESP32, ESP8266, NXP, TI chipsets etc 10. Wireless Products, Battery Operated, Low Power, Low cost 11. Design Optimization - Could optimize design of any product by at least 25% 12. Design for Quality, Design Review 13. PCB Prototyping, Contract Manufacturing 14. Firmware Development - ARDUINO, C, C++ etc 15. Enclosure Design, 3D Printing, Sheet Metal, 16. Production Support 17. EMI EMC Compliant Design - RE, EMHF, Surge, EFT, Burst, Impulse, 35KV 18. Standards Experience - UL, CISPER, CE, Please contact me if you would like to develop a robust and reliable product If you are looking to bring your idea to life, contact me :)

As an Engineer and inventor with over 15+ years of professional experience, I thrive on developing products that meet today's technical challenges head-on. My career has been a fusion of rigorous curiosity and precise technical skill, topping in a deep well of expertise that’s ready to tackle your project. Here's a snapshot of the domains I've grasped: Hardware Specialties 💻🔌 ✅ Embedded systems: programming, hardware design, and firmware development from concept to execution, including ARM-based controllers, DSP, and FPGA technologies. ✅ PCB Design: Expert in designing layouts and schematics, bringing circuits to life flawlessly. Wireless Communication: Proficient with Bluetooth, WiFi, RF protocols, and crafting IoT devices that empower smart connectivity. ✅ Sensor Savant: MEMS / IMU, GPS tracking, and biometric identification through RFID and fingerprint technology. ✅ Design Tools: Proficient with industry-leading software such as Altium Designer, Eagle CAD, KiCAD, Proteus, etc. Software Proficiency 👨‍💻📲 ✅ App Development: Crafting responsive, user-friendly web and mobile apps optimized for IoT solutions, enhancing functionality and user experience. ✅ Web Design & Deployment: Custom WordPress solutions, e-commerce, APIs, and more. ✅ Coding Languages: Kotlin, Java, C++, and C# form the foundational backbone of my custom software solutions. ✅ Data Handling: Experienced in CMS, API integrations, and web scraping for robust, seamless user experiences. Mechanical Design Services 🧰 ✅ Enclosure Designing: Merging technical requirements with aesthetic considerations to design custom enclosures that heighten the value and usability of electronics. 🚀 I'm excited to collaborate and bring your vision to completion, incorporating your innovative ideas with my technical know-how to leave a mark on the future. Tags: Electrical Engineer, Electrical Engineering, Electronics, Hardware, Firmware, PCB, PCB layout, Board Layout, Schematics, Altium Designer, IoT, Internet of Things, Power Electronics, Bluetooth, BLE, TI, Texas Instruments, FPGA, SoC, VHDL, Verilog, Xilinx, Altera, VHDL, C, C++, MCU, RTOS, Microcontroller, prototype, validation, Enclosures, BMS, SolidWorks, Android, iOS, Java, Swift, Mobile Apps, Database, React, AWS, Python, ESP32, Arduino, PLATFORMIO, PIC, NXP, Texas Instrument, Nordic, DIALOG, STM32, LCD, Raspberry Pi, Robotics, Oil and Gas Automation, RF, XBEE, Wi-Fi, BLE, Production, Prototyping, LoRa WAN, Manufacturing, Assembly, Motor Driver, Prototype, Wireless Module, Controllers, PLC, CREO, Industrial Designer, EASY EDA, KiCAD. Warm Regards, Huzaifa Ali

With over 20 years of experience in Electronics and Embedded systems engineering, I'm a wizard at turning innovative ideas into cutting-edge solutions. As the founder and lead engineer of High Technologies Solutions, I've led the development of more than 40 successful released into-production projects across North America, Western Europe, and Australia. Whether you're an inspired individual, a small start-up, or a large corporation - I'm passionate about helping you bring your ideas to life with tailored, and cost-effective leading industry-level solutions. Wearable and Smart Electronics, Home appliances, MedTech, EV, Green Energetic, and Industrial areas - I've worked on projects that have made a real difference in people's lives. What sets me apart is the all-in-one comprehensive service and my commitment to staying up-to-date with the latest industry trends and technologies. I'm always looking for new and better ways to approach a project, and I'm not afraid to think outside the box to deliver results that exceed your expectations. So, whether you're a tech guru or a non-tech individual with an innovative idea, I'm the one you can trust to bring your vision to life. Let's work together to make your dreams a reality! ✅ What I can do for you? - Electronics engineering - Prototyping - PCB design (Precision, Low Noise, Flexible, Multi-layer) - Hardware & Firmware engineering (Analog, Digital, Power) - Software, Mobile App, and Server solutions development - Technology and cost optimization - Mass production optimization Technologies stack (but not limited to): Hardware: STM32, ESP, nRF, TMS, FPGA, PLD / CPLD, AVR, Fujitsu, Z-80, AC/DC, DC/DC, Power Electronics Languages/ Technologies: Embedded C / C++, Assembler (Cortex-M, AVR), Reverse Engineering, PHP, RUBY, JS, Solidity, Mysql, NoSQL, Redis, HTML / CSS / SCSS, API integration, Web3, Сonsole C, Altium, KiCad, P-CAD, Sprint layout, Solidworks, Orcad, Diptrace Clouds: AWS IoT Protocols / Standards: GSM / GPRS / LTE, MQTT, SSL / TLS, HTTP / HTTPS, Bluetooth, WiFi, RF, TCP, GNSS, GPS Interfaces: I2C, SPI, UART, CAN, RS, SDIO, PWM, Analog, LoRaWAN, LVDS

Experienced System Engineer & Academic Writer Ready to Elevate Your Projects 🚀 Greetings! I'm Yosef, a seasoned System Engineer with a passion for crafting impactful technical and academic content. Over the past two years, I've been delivering top-notch solutions on Upwork, catering to diverse clients with a wide array of needs. 🔬 Technical & Academic Expertise: Whether it's delving into complex system engineering concepts or crafting insightful academic papers, I bring a wealth of knowledge and experience to the table. My proficiency spans technical content creation, academic writing, and expertise in LaTeX for polished document formatting. 💻 SaaS & Virtual Assistance: Need assistance with SaaS implementations or virtual support for your projects? Look no further! I specialize in providing comprehensive virtual assistance services, ensuring seamless project management and execution. 📊 Data Entry & Research: Accuracy and efficiency are paramount in data entry and research tasks, and I pride myself on delivering both. From meticulous data entry to in-depth research, I am dedicated to meeting and exceeding your expectations. 🌟 Why Choose Me? 🌟 Reliability: You can count on me to deliver high-quality work within deadlines. Expertise: With a background in system engineering and academic writing, I offer a unique blend of technical prowess and academic rigor. Communication: Clear and prompt communication is key to successful collaboration, and I prioritize keeping you in the loop every step of the way. Let's collaborate to turn your visions into reality! Drop me a message, and let's discuss how I can contribute to your projects.

I am a PhD-Level experienced Antenna Design Engineer and capable of handling your project from initial planning stage to implementation. ✅Education 🔻 Ph.D. in Electrical Engineering 🔻Specialization: Phased Antenna Arrays, RF/Microwave, mm Waves & THz antennas ✅ Experience 🔻I have been working in the field of RF & Microwave Antennas for the last 7 years ✅ Technical Skills. I'm an expert in 🔻CST Microwave Studio Suit 3D EM Simulation 🔻Advanced Design System (ADS) 🔻High Frequency Structure Simulation (HFSS) 🔻AWR Microwave Office 🔻Altium Designer 🔻MATLAB/Multisim/Proteus/PSpice/Codblock/C++/LabView ✅ Paper and Thesis Editing Skills I offer valuable assistance in various written tasks, including the composition of reports, extended essays, dissertations, thesis, and scientific publications. I can support you throughout the entire process, from developing the initial proposal and outlining the research to providing thorough proofreading and editing for the final document. ✅Area expertise including: 🔻Antennas (single element, Array, MIMO for 5G/6G) 🔻RF circuits & antenna matching circuits 🔻Amplifiers / Filters 🔻Power dividers / feed network 🔻Phased Antenna Arrays 🔻mmWaves & THz antennas 🔻Wideband Arrays, Dual Polarized Arrays 🔻Beamforming and Calibration, Arrays measurements 🔻MIMO and Metamaterial phased array 🔻Array signal processing 🔻Low cost commercial antennas 🔻 Antennas for medical applications To support my work, I have access to a fully equipped anechoic chamber, furnished with state-of- the-art equipment such as network analyzers, EMI test equipment, and PCB assembly tools. This ensures that the prototyping, testing, and troubleshooting phases of the projects are carried out to the highest standards. With a dedication to delivering exceptional results, I am committed to providing the highest level of professionalism and expertise to every project I undertake. ✅Recent Publications: [1]. Ayaz, M., & Ullah, I. (2023). A Singly Curved Conformal Phased Array with Integrated Particles-Based CRLH Phase Shifters. Electronics Journal. [2]. Ayaz, M., & Ullah, I. (2023). A Phased Array Antenna with Novel Composite Right/Left-Handed (CRLH) Phase Shifters for Wi-Fi 6 Communication Systems. Applied Sciences, 13(4), 2085. [3]. Ayaz, M., Iftikhar, A., Braaten, B. D., Khalil, W., & Ullah, I. (2023). A Composite Right/Left-Handed Phase Shifter-Based Cylindrical Phased Array with Reinforced Particles Responsive to Magneto-Static Fields. Electronics, 12(2), 306. [4]. Ayaz, M., & Iftikhar, A. (2019, July). A Compact Design of Composite Right/Left-Handed (CRLH) Metamaterial Based Phase Shifter. In 2019 International Conference on Electrical, Communication, and Computer Engineering (ICECCE) (pp. 1-6). IEEE.

Experienced technical writer and SEO writer with a track record of increasing website traffic and boosting conversion rates, resulting in higher revenue for clients. Do you need help with technical content? With over two decades of experience creating technical documents that are accurate, easy to understand and get the point across, I can help you with your requirements. About Me I am an Electrical engineer with BS & MS degrees, with five years of freelance writing experience and over 16 years of experience in the telecommunication/data networking industry, designing and deploying wide-area networks for data/voice/video. What I do: 🏆 SEO-optimized content 🏆 Copywriting 🏆 YouTube Scripts 🏆 Research 🏆 Technical reports and presentations 🏆 User manuals 🏆 Editing and proofreading 🏆 Network design 🏆 Training material Tools I use: 🔎 Ahrefs / Surfer SEO ⌨️ Zendesk / WordPress 🎨 SnagIt, InDesign 🎙️ Descript 💬 Slack / WhatsApp / Telegram / Skype 📆 Asana CLIENT TESTIMONIALS "Faisal demonstrated a phenomenal attention to detail, punctuality, professionalism, and kindness for the duration of our project. He also brings a wealth of practical and theoretical knowledge on many tech topics." "Faisal was very responsive, did a great job on the materials provided and was very good about asking for feedback to improve his product. If we have more requirements of this nature in the future I would not hesitate to reach out to Faisal." "We have been delighted with the work from Mr. Faisal due to his go-to mindset. He has been great to work with and has put much effort into the work he has done. Every delivery has exceeded our expectations, and we would definitely recommend him for your content creation projects." "Faisal does great work. He is a skilled writer, and his grasp of marketing copy is excellent. I would highly recommend this freelancer for your next writing project." "Faisal was excellent to work with and quite responsive to our needs. He is a solid English writer." "Shaikh was a pleasure to work with and I highly recommend him for your proofreading, editing project. He is very polite, professional and offers editing ideas that improve and enhance your project. I would definitely use him again"

I am a professional Electronics Engineer with six years of experience in the Embedded System Software and Hardware R&D industry. My expertise range from hardware design with firmware development to the integration of hardware with software(Web. IOS, Android). I strive to provide low-cost embedded solutions. My knowledge of engineering specifications that rule each production stage is well defined, and I take pride in my ability to work in sync with resources and people ⚡Expertise in Hardware Design & PCB Design⚡ ✅Schematic Capture and PCB Design by using the Altium Designer, Eagle, Ki-cad. ✅High-speed complex PCBs. ✅PCBs with FPGAs, Processors, DDR2, DDR3, PCIe, HDMI, Ethernet, USB 3.0. ✅PCBs with SPI, I2C, RS232, RS485, RS422, CAN, USB, UART Protocol circuits. ✅Design Layout for 4G/LTE, Wi-Fi Module, Bluetooth, GSM/GPS, LoRa, Zigbee. ✅Differential signal and transmission line routing. ✅Impedance calculation & Stack-up Building. ✅Knowledge of EMI/EMC and CE certifications. ✅EMI/EMC Compliant Design ✅RF PCBs with Rogers & FR-4 with complete impedance calculation. ✅Digital & Analog(Mix signal PCBs). ✅Power Electronics circuit design. ✅Multi Stack boards enclosed in casings. ✅Shields of all Arduino boards and Raspberry Pi boards. ✅IoT PCBs with NB-IoT Processor chip i.e. NRF9160. ✅Biomedical-related sensors circuit board design. ✅MEMS / IMU Sensors circuit board design. ✅Motor Control circuit boards design. ✅NFC, RFID, and biometric circuit boards design. ✅Enclosure, 3D modeling, Rendering in Solid works. ✅Product Prototyping as well as preparing for manufacturing ✅Reverse Engineering of PCBs. ✅Consultancy and technical support of PCB fabrication and assembly. ⚡Expertise in Embedded Firmware Development⚡ ✅Exceptional C++/C /C# and Python programming skills. ✅FPGA design using Verilog/VHDL (Xilinx ISE). ✅Boards (ARM, TI, ST, Microchip, Atmel, DSP, Arduino, etc.) ✅Embedded software: Keil, Eclipse, Segger, Zyhper, Atmel Studio, Arduino, Node-Red. ✅Single board computer: Raspberry Pi, Beaglebone, NanoPi. ✅Strong with UART, I2C, SPI, BLE, BT, GSM/4G/LTE/GPRS/GPS, ZigBee, LORAWAN. ✅Strong with BLE HM10, HC05,ESP8266, ESP32, DA14580, nRF52,nRF9160. ✅Strong with RS232, RS485, RS422, CAN, USB2.0, USB3.0. ✅OBD Protocols SAEJ1850PWM, SAEJ1850VPW, ISO14230-4 (KWP2000),ISO15765-4. ✅IoT development using MQTT. ✅Expert in AWS IoT Core and Azure IoT Core ✅IoT Development in NODE RED Environment on Raspberry Pi(Raspbian). ✅Experience in NRF connect. I am hoping to be hired by you to bring your project to completion in the least time with a nominal price by using My skills and experience. If given a chance to do this task, I will work best and bring in the required output.