By inventing the wireless transmitter or radio in 1897, the Italian physicist Tomaso Guglielmo Marconi added a new dimension to the world of communications. This enabled the transmission of the human voice through space without wires. For this epoch-making invention, this illustrious scientist was honored with the Nobel Prize for Physics in 1909. Even today, students of wireless or radio technology remember this distinguished physicist with reverence. A new era began in Radio Communications.
標簽： Radio Frequency Modulation
上傳時間： 2020-06-01
上傳用戶：shancjb
This paper presents a Hidden Markov Model (HMM)-based speech enhancement method, aiming at reducing non-stationary noise from speech signals. The system is based on the assumption that the speech and the noise are additive and uncorrelated. Cepstral features are used to extract statistical information from both the speech and the noise. A-priori statistical information is collected from long training sequences into ergodic hidden Markov models. Given the ergodic models for the speech and the noise, a compensated speech-noise model is created by means of parallel model combination, using a log-normal approximation. During the compensation, the mean of every mixture in the speech and noise model is stored. The stored means are then used in the enhancement process to create the most likely speech and noise power spectral distributions using the forward algorithm combined with mixture probability. The distributions are used to generate a Wiener filter for every observation. The paper includes a performance evaluation of the speech enhancer for stationary as well as non-stationary noise environment.
標簽： Telecommunications Processing Signal for
上傳時間： 2020-06-01
上傳用戶：shancjb
Second-generation telecommunication systems, such as the Global System for Mobile Communications (GSM), enabled voice traffic to go wireless: the number of mobile phones exceeds the number of landline phones and the mobile phone penetration is approaching 100% in several markets. The data-handling capabilities of second-generation systems are limited, however, and third-generation systems are needed to provide the high bit-rate services that enable high-quality images and video to be transmitted and received, and to provide access to the Web with higher data rates.
標簽： Evolution WCDMA UMTS HSPA LTE for and
上傳時間： 2020-06-01
上傳用戶：shancjb
For more than three decades, Micro Electro Mechanical Systems (MEMS) have steadily transitioned out of research labs and into production forming a more than $10 billion market [1]. MEMS devices such as accelerometers, pressure sensors and microphones, to name a few, have seen immense utilization, particularly in the consumer electronics market, because of their compact sizes and minute power consumptions. In addition, these devices benefit from batch fabrication, which has enabled year-over-year reductions in cost [2]. In recent years,
上傳時間： 2020-06-06
上傳用戶：shancjb
It has been said that the move from narrowband to broadband access is the second revolution for the Internet — ‘broadband is more bandwidth than you can use’. Once users have experienced broadband access there is no turning back. A whole new world of applications and services becomes possible. No longer is it the ‘world- wide wait’. The speed of response and visual quality enabled by broadband finally allows the Internet to reach its true potential.
上傳時間： 2020-06-06
上傳用戶：shancjb
Since the original publication of Manual 74 in 1991, and the preceding “Guidelines for Transmission Line Structural Loading” in 1984, the understanding of structural loadings on transmission line structures has broadened signifi cantly. However, improvements in computational capa- bility have enabled the transmission line engineer to more easily deter- mine structural loadings without properly understanding the parameters that affect these loads. Many seasoned professionals have expressed concern for the apparent lack of recent information on the topic of struc- tural loadings as new engineers enter this industry. The Committee on Electrical Transmission Structures is charged with the responsibility to report, evaluate, and provide loading requirements of transmission struc- tures. This task committee was therefore formed to update and revise the 1991 manual.
標簽： Transmission Guidelines Electrical Line for
上傳時間： 2020-06-07
上傳用戶：shancjb
Commercial energy storage has moved from the margins to the mainstream as it fosters flexibility in our smarter, increasingly integrated energy systems. The energy density, availability, and relatively clean fossil profile of natural gas ensure its critical role as a fuel for heating and electricity generation. As a transportation fuel, natural gas continues to increase its market penetration; much of this has been enabled by emerging developments in storage technology.
標簽： Hydrogen Methane Storage Energy and for
上傳時間： 2020-06-07
上傳用戶：shancjb
adio Frequency Identification (RFID) is a rapidly developing automatic wireless data-collection technology with a long history.The first multi-bit functional passive RFID systems,with a range of several meters, appeared in the early 1970s, and continued to evolve through the 1980s. Recently, RFID has experienced a tremendous growth,due to developments in integrated circuits and radios, and due to increased interest from the retail industrial and government.
標簽： RFID-Enabled Sensors RFID and
上傳時間： 2020-06-08
上傳用戶：shancjb
Radio frequency identification (RFID) is gaining in popularity, especially as we find ourselves in this communications age and headed towards a ubiquitous computing world. Automatic identification systems become an important aspect not just in today’s technology but also as part of our daily life. We need RFID in our cars, transportation systems, access points, and even simple transactions; we also acknowledge the need for RFID in our logistics systems, healthcare, and tracking and locating applications.
標簽： RFID-Enabled Appications Design Sensor and
上傳時間： 2020-06-08
上傳用戶：shancjb
With more than two billion terminals in commercial operation world-wide, wire- less and mobile technologies have enabled a first wave of pervasive communication systems and applications. Still, this is only the beginning as wireless technologies such as RFID are currently contemplated with a deployment potential of tens of billions of tags and a virtually unlimited application potential. A recent ITU report depicts a scenario of “Internet of things” — a world in which billions of objects will report their location, identity, and history over wireless connections.
標簽： Internet Things From The RFI of
上傳時間： 2020-06-08
上傳用戶：shancjb
<button id="isicm"></button>