Filterability improvement

Precise definition of receiver bandwidth by means of audio filters (improves sensitivity). 

The z-filter In spinlock sequences and selective ID COSY experiments the z-filter improved the artefact suppression of accumulated experiments. 

The combined transfer function r(tn) for ETDAS and low-pass filtering is displayed in Fig. 5.6(b). As in Fig. 5.6(a), there are notches at multiples of the frequency of the UPO, which become narrower for increasing R. The amplitudes of frequencies larger than the cut-off frequency a are reduced and thus are only minor contributions to the feedback response. This is important to notice in order to understand how the low-pass filter improves the controllability of the system. 

This technique successfully reverses the MFCC coding operation. The main weakness is that, because we threw away the harmonic information in the filter-hank step, we have to resort to a classical LP-style technique of using an impulse to drive the LP filter. Improvements to this have been made, with the motivation of generating a more-natural source, while still keeping a model system in which the parameters are largely statistically independent. For example, the technique of Yoshimiu a et al. [509] uses various excitation parameters that allow mixing of noise and impulse, and allow a degree of aperiodicity in the positions of the impulses. 

Examples of manufacturing properties and advantages include better filtering, improved flow, less caking, better drying, lower hygroscopicity, greater... 

We must emphasize the difference in the character of the adhesion to a dust-free (fresh) and a dusty filter, particularly for highly dispersed dusts. The dust-holding capacity of filters improves sharply as they gather dust the secondary porous barrier formed by the particles of dust deposited in the pores between the fibers or grains of the filter are more efficient in trapping particles as a result of diffusion and contact. 

Figure 9). Photographic images obtained with the electron microscope can be sharpened using laser techniques to remove the fuzziness. In its most spectacular application, the holographic filter improved the resolution of electron micrographs to 2.5 A and revealed, for the first time, the helical structure of a virus. 

One remaining possibility that is less costly from an energy point of view but needs to be carefully controlled is to incorporate additives called flow improvers. These materials favor the dispersion of the paraffin crystals and in doing so prevent them from forming the large networks which cause the filter plugging. The conventional flow improvers essentially change the CFPP and pour point, but not the cloud point. They are usually copolymers, produced, for example, from ethylene and vinyl acetate monomers ... 

The nature of these paraffins and their concentration in diesel fuel affect the three temperatures that characterize the cold behavior. The cloud point is the temperature at which crystals of paraffins appear when the temperature is lowered. The cold filter pluming point is defined as the temperature under which a suspension no ionger flows through a standard filter. Finally, the pour point is the temperature below which the diesel fuel no longer flows by simple gravity in a standard tube. These three temperatures are defined by regulations and the refiner has three types of additives to improve the quality of the diesel fuel of winter. 

The main goal of ultrasonic grain noise suppression in material flaw detection is to improve the perceptual possibilities of the operator to observe defect echoes. The suppression is defined as perceptually ideal when a received signal (or image) which contains echoes buried in noise is filtered to yield nonzero values only at the positions of the defect echoes. 

In statistical terms, a perceptual improvement is therefore obtained if the amplitude distribution in the filtered signal (image) is more concentrated around zero than in the raw data (contrast enhancement). A more concentrated amplitude distribution generally means smaller entropy. Thus, from an operator perception point of view, interesting results should be obtained if the raw data can be filtered to yield low entropy amplitude distributions. However, one should note that the entropy can be minimized by means of a (pathological) filter which always outputs zero or another constant value. Thus, appropriate restrictions must be imposed on the filter construction process. 

By choosing the proper correlation algorithm, it is possible to realise sensitive filters for other types of defects (e.g. corrosion). Fig. 5.2 shows an example for the suppression of signals which do not exhibit the expected defect stmcture (Two parallel white lines near upper central rim portion of Fig. 5.2). The largest improvement in SNR is obtained here by using the expression (ai ai+x /ai+yj), since for a gradiometric excitation, one expects the crack response to show two maxima (a, aj+x) with a minimum (a m) in the centre (see Fig. 5.3). 

The approach of using so-called adaptiv filters which are already widely accepted in telecommunications and have greatly improved the quality of voice transmission seems to be promising as well. 

A 3D summation tomographic image is generated and layers in any direction may be viewed. Image quality is improved by filters. The method has been proved satisfactory on a high radiographic contrast cylindrical object and on more complex items. 

The image generated by the image intensifier was found to be very sensitive to noise and to reduce this effect, a low pass filter was included. This filter has greatly improved the final 3D... 

Three approaches have been identified that reduce susceptibility of CA resists to airborne contamination. In the first, process engineering changes such as the addition of special activated carbon filters to the environmental chambers surrounding the exposure tools (76,79), overcoating the resist with a soluble protective film to isolate the resist from the environment (77,80,81), or modifications of the process flow to minimize the time interval between exposure and post-exposure bake have been shown to improve CA resist processibibty. 

Improvements ia membrane technology, vahdation of membrane iategrity, and methods to extend filter usage should further improve the performance of membrane filters ia removal of viral particles. Methods to improve or extead filter life and iacrease flow rates by creating more complex flow patterns could possibly be the focus of the next generation of membrane filters designed to remove viral particles. 

Pretreatment of Suspensions. Another important aspect of soHd—Hquid separation is conditioning or pretreatment of the feed suspension to alter some important property of the suspension and improve the performance of a separator that follows. A conditioning effect is obtained using several processes such as coagulation and docculation, addition of inert filter aids, crystalliza tion, freezing, temperature or pH adjustment, thermal treatment, and aging. The first two operations are considered in more detail due to their importance and wide use. 

In the precoat and body feed mode, filter aids allow appHcation of surface filtration to clarification of Hquids, ie, filtration of very dilute suspensions of less than 0.1% by volume, such as those normally treated by deep bed filters or centrifugal clarifiers. Filter aids are used in this mode with pressure filters. A precoat is first formed by passing a suspension of the filter aid through the filter. This is followed by filtration of the feed Hquid, which may have the filter aid mixed with it as body feed in order to improve the permeabiUty of the resulting cake. The proportion of the filter aid to be added as body feed is of the same order as the amount of contaminant soHds in the feed Hquid this limits the appHcation of such systems to low concentrations. Recovery and regeneration of filter aids from the cakes normally is not practiced except in a few very large installations where it might become economical. 

Benefits of Prethickening. The feed soHds concentration has a profound effect on the performance of any cake filtration equipment. It affects the capacity and the cake resistance, as weU as the penetration of the soHds into the cloth which influences filtrate clarity and medium resistance. Thicker feeds lead to improved performance of most filters through higher capacity and lower cake resistance. 

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