lò vi sóng có nướng được không

... bằng lò vi sóng thôi cũng không tốt, vì sóng viba của lò vi sóng tác động đến các tế bào chất của thực phẩm, làm biến chất thực phẩm và lâu dài gây tác hại cho người ăn thực phẩm đó. Không ... phá hủy chất dinh dưỡng hay do lò vi sóng làm cho thực thẩm mất an toàn là không có cơ sở. Mặc dù lò vi sóng - cũng như mọi Vi c đun nấu sẽ làm giảm bớt hàm lượng vitamin trong thực phẩm ở một ... cũng không ít người lo ngại về tác dụng của lò vi sóng đối với thực phẩm. Tuy nhiên, TS Kristin Hendrickson, ngành hóa sinh, Đại học Bang Arizona (Mỹ) cho rằng, lo ngại về vi c sóng viba có...

Ngày tải lên: 29/06/2014, 06:20

Ngày tải lên: 29/06/2014, 16:20

Ngày tải lên: 10/08/2014, 07:20

... various services such as voice mail, email, video, messaging, data, and computer on-line services. The direct link between satellites and personal communication systems can provide voice, video, ... Chapter 2 reviews some fundamental principles of transmission lines and electromagnetic waves. Chapter 3 gives a brief overview of how antennas and antenna arrays work. Chapter 4 provides a discussion FIGURE ... (DBS) systems have offered an alternative to cable television, and the end of the Cold War has made many military technologies available to civilian applications. The global positioning systems (GPSs),...

Ngày tải lên: 24/12/2013, 17:15

... axis. The Smith chart can be used to ®nd (1) G L from Z L and vice-versa; (2)  Z in from  Z L and vice-versa; (3) Z from Y and vice-versa; (4) the VSWR; and (5) d min and d max . The Smith ... normalized values. 2. Moving away from the load (i.e., toward the generator) corresponds to moving in a clockwise direction. 3. A complete revolution around the chart is made by moving a distance l ... degree of accuracy, by dividing P 2 by P 1 , ®nding the logarithm of the result, and multiplying it by 10. FIGURE 2.11 Transmission line connected to an open load. 28 REVIEW OF WAVES AND TRANSMISSION...

Ngày tải lên: 24/12/2013, 17:15

... or microwave power. It is a reciprocal device, and the same antenna can serve as a receiving or transmitting device. Antennas are structures that provide transitions between guided and free-space ... the HPBW and SLLs. Also shown is FNBW, the first-null beamwidth. 3.5.5 Directivity, Gain, and Efficiency The directivity D max is defined as the value of the directive gain in the direction of its maximum ... Þ¼ 1 2 Re½ ~ EE Â ~ HH*. The directivity of an isotropic antenna equals to 1 by definition, and that of other antennas will be greater than 1. Thus, the directivity serves as a figure of merit relating...

Ngày tải lên: 24/12/2013, 17:15

... capacitances. Active filters can be built by using active devices such as MESFETs in microwave frequencies and CMOS in RF. The active devices provide negative resistance and compensate for the losses ... biasing field. Ferrite control devices are heavy, slow, and expensive. Solid-state control devices, on the other hand, are small, fast, and inexpensive. The ferrite devices do have some advantages ... the comparison between ferrite and p i n diode control devices [1]. It should be mentioned that the use of FETs or transistors as control devices could provide gain instead of loss. Switches are widely...

Ngày tải lên: 24/12/2013, 17:15

... dBm FIGURE 5.13 Third-order intermodulation. 164 RECEIVER SYSTEM PARAMETERS 2. Selectivity. Receiver selectivity is the ability to reject unwanted signals on adjacent channel frequencies. This ... sensitivity of the receiver. In order for a signal to be detected, it should have a strength much greater than the noise floor of the system. Noise sources in thermionic and solid-state devices ... the equivalent noise temperature in kelvin, (d) the minimum detectable signal (MDS) in dBm at input port, and (e) the input IP3 power level in dBm. The individual component system parameters are...

Ngày tải lên: 24/12/2013, 17:15

... Còn nếu không thích thì măm măm luôn thôi! Đã có cách làm brownie bằng lò vi sóng rồi đây! Một loại bánh với hương thơm thật quyến rũ của chocolate… và chỉ mất 6’ cho vi c nướng bánh...

Ngày tải lên: 21/01/2014, 00:20

... the reference frequency can also be divided before it is connected to the phase detector. This scheme is shown in Fig. 6.20. A fixed frequency divider with division ratio of N 2 is introduced between ... to heating of a solid-state device. Some of these characteristics can be found in an example given in Table 6.1. 6.2 TRANSMITTER NOISE Since the oscillator is a nonlinear device, the noise voltages ... high-Q circuits to build the oscillators (examples are waveguide cavities, dielectric resona- tors, or superconducting resonators=cavities); (2) temperature compensation circuits; or (3) phase-locked...

Ngày tải lên: 21/01/2014, 23:20

... receiving. A duplexer is used to separate the transmitting and receiving signals. A circulator is shown in Fig. 7.2 as a duplexer. A switch can also be used, since transmitting and receiving ... f d ð7:34Þ FIGURE 7.17 Waveform for a moving target: (a) stationary target waveform for compar- ison; (b) waveform for a target moving toward radar; (c) beat signal from a target moving toward radar. 7.7 FREQUENCY-MODULATED ... introduction and overview of radar systems are given. 7.2 RADAR EQUATION The radar equation gives the range in terms of the characteristics of the transmitter, receiver, antenna, target, and environment...

Ngày tải lên: 21/01/2014, 23:20

... À1dB Space loss dB Atmospheric loss À2dB Polarization loss À1dB Receiving feed loss À2dB Receiving antenna gain 35 dB Receiving antenna pointing error þÞ À1dB REFERENCES 1. E. A. Wolff and R. ... picture of this vision [8]. The WLAN is for wireless indoor radio communication services or high-data-rate communications. The system employs a central microcell hub (base station) that services cordless ... À1dB Space loss dB Atmospheric loss À2dB Polarization loss À0:5dB Receiving feed loss À1dB Receiving antenna gain 20 dB Receiving antenna pointing error þÞ À1dB 8.8 A microwave link is set up to...

Ngày tải lên: 21/01/2014, 23:20

... time-sharing transmission is called time division multiplexing. 3. The message is represented by a coded group of digital pulses. The effects of random noise can be virtually eliminated. TABLE 9.1 Modulation ... Japanese digital cellular time division multiple access (TDMA) radio standard; it has high power efficiency and spectral efficiency. In power-efficient, nonlinearly amplified (NLA) environments, where fully ... 2pf m tÞtð9:7Þ The maximum frequency swing occurs when sin 2pf m t ¼Æ1. Here Df is the frequency deviation, which is the maximum change in frequency the modulated signal undergoes. The amplitude...

Ngày tải lên: 21/01/2014, 23:20

... wireless communications are frequency division multiple access (FDMA), time division multiple access (TDMA), and code division multiple access (CDMA). Frequency division multiple access and TDMA are ... caused by intermodulation and sideband distortion. 10.3 TIME DIVISION MULTIPLE ACCESS AND TIME DIVISION MULTIPLEXING A TDMA or time division multiplexing (TDM) system uses a single frequency band to ... transmitter; (b) TDM of two signals; (c) data slot allocation for N signals. 10.3 TIME DIVISION MULTIPLE ACCESS AND TIME DIVISION MULTIPLEXING 297 3. Time hopping 4. Chirp Figure 10.5a shows an example...

Ngày tải lên: 21/01/2014, 23:20

... applications: for example, mapping road networks, land and aviation scenarios, analyzing urban growth, and improving aviation and marine services. 4. Military applications: for example, surveillance, ... typical radio navigation systems are shown in Table 11.1 for comparison. The Omega FIGURE 11.1 Active radio navigation system. FIGURE 11.2 Passive radio navigation system. 11.1 RADIO NAVIGATION AND ... divided into three major activities: electro- nic support measure (ESM), electronic countermeasures (ECMs), and electronic counter-countermeasures (ECCMs). Figure 11.14 summarizes these activities...

Ngày tải lên: 21/01/2014, 23:20

... Nếu chiếc lò vi sóng nhà bạn chỉ để hâm nóng thức ăn thì có lẽ bạn đã hơi xem thường “năng lực” của “anh bạn” bếp núc này rồi. Có ti tỉ cách chế biến món ăn với chiếc lò giản dị này, ... cho lò vi sóng (thêm chút muối nếu muốn). Bật lò ở mức cao nhất, nấu trong 15-18 phút cho đến khi cơm dẻo đều. Ảnh: Real Simple. Bắp nguyên trái lột sạch vỏ, đặt trong đĩa viba. Bật lò ... chưa biết thì quả là bạn đã phí tiền mua lò vi sóng rồi! Làm mềm bơ trong 20 giây, lò bật mức thấp. Ảnh: Real Simple. Đun chảy bơ trong 30 giây, lò bật ở mức trung. Ảnh: Real Simple ...

Ngày tải lên: 21/02/2014, 16:20

Ngày tải lên: 03/07/2014, 03:20

Ngày tải lên: 09/07/2014, 16:20

Ngày tải lên: 10/07/2014, 04:20

Ngày tải lên: 23/07/2014, 04:20