DDS also refers to drug delivery system.
DDS is a good curing agent in chemistry, which is called 4,4' diaminodiphenyl sulfone.
Chinese name: DDS mbth: Interpretation of Direct Digital Frequency Synthesizer: Properties of Direct Digital Frequency Synthesizer: definition, advantages, chip introduction, arbitrary waveform, function, generator, dynamic switching, group detection station, Qin Cheng Express Company, dry matter, image format, scheduling algorithm, drug administration, Studio, diphenyl sulfone, data distribution, definition of DDS and DSP (digital signal processing). DDS is short for Direct Digital Frequency Synthesizer. Compared with the traditional frequency synthesizer, DDS has the advantages of low cost, low power consumption, high resolution and fast conversion time. It is widely used in telecommunications, electronic instruments and other fields, and is the key technology to realize full digitalization of equipment. DDS chip mainly includes three parts (such as Q2220): frequency control register, high-speed phase accumulator and sine calculator. The frequency control register can be loaded in serial or parallel mode and temporarily store the frequency control code input by the user; The phase accumulator carries out phase accumulation in each clock cycle according to the frequency control code to obtain a phase value; The sine calculator calculates the digital sine wave amplitude of the phase value (the wafer is usually obtained by looking up the table). The output of DDS chip is usually digital sine wave, so it needs high-speed D/A converter and low-pass filter to get usable analog frequency signal. Dds In addition, some DDS chips also have the modulation functions of amplitude modulation, frequency modulation and phase modulation, and there is a D/A converter (such as AD7008) on the chip. Advantages: high frequency resolution, many output frequency points, up to the nth power of 2 (n is the number of bits of the phase accumulator); The frequency switching speed is fast, DDS is an open-loop system without any feedback link, so the frequency switching time is extremely short, which can reach ns order; The phase is continuous during frequency switching; Can output broadband orthogonal signals; The output phase noise is low, which can improve the phase noise of reference frequency source; Any waveform can be generated; Full digital realization, easy integration, small size and light weight. Signal source plays an extremely important role in testing and application in all walks of life. However, there are many types of signal sources, and different types of signal sources have different functions and characteristics and are suitable for many different applications. Waveform generator, function generator, RF signal source and basic analog output module. Using DDS technology in signal source has gradually become the mainstream practice in the current test and measurement industry. Introduction of DDS main chip Introduction of main chip Introduction of arbitrary waveform Arbitrary waveform generator (AWG) usually provides deep memory, large dynamic range and wide bandwidth to meet various applications, including communication, semiconductor and system testing. AWG receives user-defined data from PC and uses these data to generate arbitrary waveforms. Users of AWG can download a series of waveforms they want to generate into the memory of the instrument. In general, actual waveforms and waveform sequence instructions needed to form these waveforms can be stored. Please look at the basic architecture of AWG. To generate waveforms from AWG, you must first create any waveforms themselves. Analog waveform editor, modulation tools and software tools such as LabVIEW of National Instruments Corporation (NI) can simplify the creation of these waveforms. These waveforms and their waveform sequence instructions are stored in the RAM provided by the instrument. The waveform generation sequence usually begins with TTL hardware trigger. Various waveforms are composed of many individual samples, and the sampling rate is determined by the sampling clock of the instrument. There are several different modes to obtain the sampling clock from the internal sampling clock time base (100 MHz VCXO), including DDS timing Div/N clock and several modes to provide different external clocks. In addition, the reference frequency of PLL used in the instrument has several different choices. The waveform reaches the digital-to-analog converter (DAC) through the memory, and the DAC converts the digital samples into the required analog output waveform. Before DAC, the samples are digitally filtered, and after DAC, the analog output passes through the analog filter. These digital and analog filters improve the sampling rate through interpolation, and filter out parasitic signals through harmonic low-pass filters, thus greatly improving the signal quality. Usually, these filters can be programmed by software. AWG allows users to specify waveform segments and build complex waveforms through repetition. Because AWG stores the waveform in its own memory, the waveform length is limited. Waveform cycling helps to generate a signal with multiple repeated sub-segments. Cyclic waveform segments improve storage efficiency and increase the duration of waveforms. AWG can also specify different stages in the waveform, and each stage can include different waveform segments and different periods. AWG generates each defined waveform segment in turn. By combining the sequence and the number of cycles, a very complex waveform can be constructed with a small storage capacity. AWG can specify different waveform segments for each segment, but the phase at the transition point between different segments is not necessarily continuous. Finally, many AWG have a copy function generator function. At this time, when a standard function waveform needs to be output, it can be generated by software, downloaded to AWG, and then output by AWG. This is different from the full DDS technology that will be introduced below. The function generator generates a fixed waveform, such as sine wave, square wave (rectangular wave), step wave or triangular wave (sawtooth wave), and the frequency is adjustable. The function generator does not need continuous input from the computer or mass storage buffer, because the device itself can generate these waveforms. Avr dds function generator can be based on analog technology or digital technology. Analog function generator uses analog hardware to generate simple functions, which are often used when static sine wave or square wave with specified frequency is needed. The digital function generator uses direct digital synthesis (DDS), DAC, digital signal processing and a one-cycle storage buffer to generate signals. DDS technology relies on digital control method and uses a single reference clock frequency to realize analog frequency source. DDS can realize high precision, high resolution, high temperature stability, high broadband and arbitrary and continuous phase-frequency switching. Many signal sources generate clock signals by dividing the internal time base by integers. This method is called N-division method. However, dividing by n can only produce a limited clock frequency. AWG, even several clock frequency generators, can use DDS technology to generate clock signals with very fine update frequency, which can not be achieved by dividing the frequency by n. The function waveform of a complete period of the generator is stored in the memory look-up table shown above. The phase accumulator tracks the current phase of the output function. In order to output a very low frequency, the phase difference (δ) between the sampled samples will be very small. For example, a very slow sine wave may have a delta phase of 1 degree. Then the No.0 sampling sample of the waveform takes the amplitude of the sine wave at 0 degrees, while the No.0 sampling of the waveform will take the amplitude of the sine wave at 1 degrees, and so on. After 360 samples, all 360 degrees of the sine curve, or exactly one period, will be output. A faster sine wave may have a delta phase of 10 degrees. Therefore, 36 samples will output a sine wave with one cycle. If the sampling rate remains the same, the frequency of the slower sine wave will be 10 times slower than that of the faster sine wave. In addition, a constant δ phase will inevitably lead to a constant sine wave frequency output. However, DDS technology allows the δ phase of the signal to be changed quickly through the frequency table. The function generator can specify a frequency table, which includes segments composed of waveform frequency and duration information. The function generator generates each defined frequency band in sequence. By generating the frequency table, complex frequency scanning signals and frequency hopping signals can be constructed. DDS allows the phase of the signal generator to change continuously from one stage to another. Vector signal generator provides high flexibility and powerful solutions, which can be used in scientific research, communication, consumer electronics, aerospace/national defense, semiconductor testing and some emerging fields, such as software radio, radio frequency identification (RFID) and wireless sensor networks. Some companies also provide many other analog output products, which use DAC to generate analog signals. The basic architecture of analog output board is to connect a small FIFO memory to a DAC. Most analog output boards are used to generate static voltage, and many can be used to generate low-frequency waveforms. DDS: Dynamic Display Switching (DDS): that is, when switching between mobile phone mode and Pad mode, the running application will not be interrupted. PadFone, as the first morphing mobile phone in the industry, realizes instant switching between mobile phone interface and tablet interface through dynamic display switching. As we all know, due to the different screen sizes and layouts of mobile phones and tablet computers, many programs are difficult to apply to both mobile phones and tablet devices. In order to get a good experience, an application should install both the mobile version and the flat version, which will undoubtedly affect the user experience. After the development of dynamic display switching technology, the APP application can switch smoothly between mobile phone mode and tablet mode, and can be used without reopening, so that users can get a perfect "deformed" application experience. This also requires the APP application * * * Qi Xin to work together to provide users with the most perfect enjoyment: Dan Detective College Chinese translation: Detective College Detective College emblem Meaning: Libra is a symbol of justice, and the right side of Libra is intuition, analysis and insight that can see through the truth; On the left of Libra is the courage, determination and action to track down the murderer. Keeping a sense of balance is a necessary quality for a detective. The wings spread above Libra mean that students want to express themselves to the maximum extent. Qin Cheng Express Company Beijing Qin Cheng Express Company is also called Beijing Millennium Pigeon Express Company, or dds for short. Its registered address is No.85, Pingfang, Shuangqing Road, Haidian District, Beijing, and its headquarters is in Shenzhen. 1 99765438+1October1,in Room 1506, Haiyan Building, Luohu District, Shenzhen, a DDS express company with only three people was born. /kloc-for 0/2 years, it is such a company without a penny of foreign aid, a customer and a network. It was developed entirely by self-reliance, hard struggle and self-accumulation. Up to now, it has become a large-scale private enterprise with more than 6,000 employees and more than 500 vehicles, which is spread all over the network of large and medium-sized cities in China and enjoys a good reputation in the domestic express delivery industry. The company wholly owns dozens of domestic branches in Hong Kong, Guangzhou, Dongguan, Shanghai and Beijing. More than 800 self-built service outlets, with a processing area of over 654.38+10,000 square meters. It took millions of dollars to introduce automatic assembly line sorting equipment, all of which were computerized, all departments implemented computer office, and established an online inquiry and tracking service system. But at the beginning of 20 10, DDS Express Company closed down. Founded in 1997, DDS Company has more than 6,000 employees all over the country and is a famous "low-price killer" in the domestic express delivery industry. From the debt collection disputes caused by the collapse of DDS Express, it can be seen that the low entry threshold of logistics industry is the chief culprit of uneven quality and excessive expansion of logistics enterprises. How to improve the entry threshold of express delivery industry and how to improve the existing norms of express delivery industry have become unavoidable problems. How to effectively regulate the situation of loose sand and prevent similar incidents is the most important thing. DDS (Dried Distiller's Grains Residue) is a dry distiller's grains feed made by solid-liquid separation of alcohol distiller's grains and dehydration and drying of the filtrate. The image format dds is the abbreviation of DirectDraw Surface. It is actually the product of DirectX texture compression (DXTC). DXTC reduces texture memory consumption by 50% or more. There are three formats of DXTC, namely DXT 1, DXT3 and DXT5. Many dds files can be seen in the material system of OrigoEngine. We can simply think that these dds files record the information of a picture just like bmp, tga and other common picture formats. If we use dds plug-ins in photoshop, we can open these files in photoshop. Deadline-driven scheduling algorithm DDS(deadline-driven scheduler) The earliest deadline time priority algorithm EDF is a dynamic priority scheduling algorithm proposed by Liu and Layland, also known as deadline-driven scheduling algorithm DDS. The concept of drug delivery system appeared in the early 1970s, and it became a hot spot in preparation research in 1980s. Research purposes DDS refers to the research purpose of drug delivery system, which is the abbreviation of drug delivery system. It is to achieve the best therapeutic effect with the minimum dosage in an appropriate dosage form and mode of administration. With the rapid development of drug therapy, represented by drugs with very strong pharmacological activity, many drugs that must be paid enough attention to when using drugs have been systematically developed, and the concept of "drug optimization" has gradually become a very concerned issue. This is mainly to achieve the best medication form and control the drug concentration as much as possible according to the choice or need? Time mode, delivered to the action and expression site of drugs, to achieve the safety of therapeutic drugs. However, it is difficult to do this by traditional methods. By using new technologies and methods to adjust the dynamic changes of drugs in vivo, medication methods and drugs centered on obtaining the best therapeutic effect are being developed. This is the drug delivery system, named after a language that can express its own concepts. Although they are all controlled by the dynamic process of various drugs in the body, they are also divided! (1) controlled release; (2) Developing new routes of administration to overcome the obstacles of drug absorption; (3) aiming and other three ways. DDS Studio Tintin Studio was established in 2008. It is located in the northeast corner of the intersection of Xi 'an Wei Second Street, on the third floor of landscape clothing. It is the largest street dance club in northwest China. Jazz coach Tintin has won many national street dance competitions. Sun Tao, a street dance coach, was the referee of the 2008 M-Zone Xi Division. Basic information of diphenyl sulfone (English name: diaminodiphenyl sulfone). : C 12H 12N2O2S molecular weight: 248.29casNo.: 80-08-0 quality specification: appearance: white crystals or physical properties of powder. White or yellowish crystalline powder, odorless, bitter in taste, melting point: 175- 176℃ relative density (water = 1) 1.33 insoluble in water, toxic in acetone and alcohol, flammable and need to be thoroughly cleaned after storage and transportation. Take off the contaminated clothes and clean them before reuse. Prevent contact with eyes, skin and clothes, and prevent ingestion and inhalation. Store in a cool and dry place. Please close the lid when not in use. Uses: It is used to synthesize polysulfone amide resin and other polymers, epoxy resin curing agent, and anti-leprosy drugs. The above usage is used for data distribution service (DDS) in aerospace, insulating materials, medicine and other fields, which defines an efficient service for distributing data among participants of distributed application programs. This service is CORBA neutral. The specification provides a platform-independent model (PIM) and a platform-specific model (PSM). The implementation of IDL mapped to CORBA is PIM. The service is divided into two interfaces: data-centric publish-subscribe (DCPS) layer and local application optional data reconstruction layer (DLRL). The DCPS layer uses QoS constraints to transmit data from publishers to users. The system includes data subject, publisher and user. If the data is local, DLRL allows local objects to share distributed data remotely. DLRL is built on DCPS layer. One of the better open source implementations is OpenDDS.