Known Problems

The camera model has a high number of parameters with a high correlation between several parameters. Therefore, the calibration problem is a difficult nonlinear optimization problem with the well known problems of instable behaviour and local minima. In out work, an approach to separate the calibration of the distortion parameters and the calibration of the projection parameters is used to solve this problem. 

In misting areas, exercise special care in maintaining paint layers. Regularly inspect known problem areas. 

Long before chiral allenes were known (Problem 9.72), the resolution of 4-methylcyclohexylideneacetic acid into two enantiomers had been carried out. Why is it chiral What geometric similarity does it have to allenes ... 

Systemic muscle damage, often associated with pain and discomfort, is a well known problem associated with specific drugs such as epsilon amino caproic acid (EACA), clofibrate, emetine, vincristine, chloroquine, D-penicillamine, and anabolic steroids. Notes on each of these drugs follow, but for a detailed discussion of drug-induced muscle damage refer to Argov and Mastaglia (1988) and Harris and Blain (1990). 

Chemical research is driven by many goals, and it progresses in many different ways. The essential traits of a good researcher are curiosity, creativity, flexibility, and dedication. Some chemical advances come from a direct assault on a known problem. A classic example is the development of the Hall process for refining aluminum from its ores, which we describe in Chapter 21,. As a contemporary example, many scientists around the world are working at a feverish pace to develop a vaccine against the AIDS virus. 

Most manufacturers perform periodie tests on their products for total microbial bioburden and for the presence of known problem mieroorganisms, to be used for in-house eonfirmahon of the eonhnuing efFieiency of their GPMP systems, rather than as conventional end-produet eonformance tests. Fluetuation in values, or the appearanee of speeific and unusual species, can warn of defects in procedure and impending problems. 

Impaired circulation, destruction of RBCs, and vascular stasis are three known problems that are responsible primarily for the clinical manifestations of SCD. These pathologic findings are likely due to HbS polymerization and RBC membrane damage (Fig. 65-3). 

Contaminated solvents and glassware are a very well known problem in analysis involving extraction. The major problem in the use of solvents is contamination with plasticisers, especially DEHP. After sample extraction usually enrichment of the analytes is required prior to the analysis. 

Underpotential deposition of heavy metals on H2 evolving electrodes is a well known problem [133], The existence of a direct correlation between H2 evolution activity and metal work function, makes UPD very likely on high work function electrodes like Pt or Ni. Cathode poisoning for H2 evolution is aggravated by UPD for two reasons. First, deposition potentials of UPD metals are shifted to more anodic values (by definition), and second, UPD favors a monolayer by monolayer growth causing a complete coverage of the cathode [100]. Thus H2 evolution may be poisoned by one monolayer of cadmium for example, the reversible bulk deposition potential of which is cathodic to the H2 evolution potential. 

But you could find customers at the other extreme of the spectrum too. In that case you may need to tell them honestly they do need to pay more attention to a certain problem you have spotted, and may in fact need to pay more to have it resolved. You can also find other vendors out there, knowingly playing down known problems to their customers, for whatever reason. In other words, you always have to be careful, whichever side of the table you are on. 

One of the first applications of the new mesh and node intramolecular circuit rules discussed above is the well-known problem in electrical circuit theory of the balancing of a Wheatstone bridge. In Fig. 21, a molecular Wheatstone bridge is presented, made of loop-like 4 tolane molecular wires bonded via benzopyrene end-groups for nano-pads 1 and 3, and via pyrene end-groups for nano-pads 2 and 4. This four-electrode and four-branch molecule is connected to a battery and an ammeter. 

Even when the path is unknown, there may be many clues about what may help. Novel problems may have some similarities to other, more well-known problems for which empirically validated interventions have been tested and developed. In such cases, those validated strategies may be modified to treat the problem at hand. In some instances, you may not have to reinvent the wheel so much as adjust it so it fits a different cart. In other cases, perhaps someone in your professional network has worked with a similar problem and can provide consultation regarding what she or he did, and whether it worked. 

It is another well-known problem that classical triblock TEP s, i.e. those of the Kraton-type, are often confined to applications under rather mild conditions, due to the relatively low Tg of the glassy phase, and/or the medium thermal stability of the rubbery phase In principle at least, good answers to that challenge can be offered by the type of synthesis discussed in this section. 

Self-association of substances with acidic hydrogens82, including amines (to form, in a first approximate model, dimers mainly by hydrogen bonding interactions), is a long known problem. There are numerous reports in the literature on the thermodynamic, spectroscopic and structural aspects of self-association and dimer formation of water, alcohols, ammonia, amines and hydrogen sulphide83. 

The latter, in contrast to nuclear Overhauser enhancement and exchange spectroscopy (NOESY), always feature positive NOEs (negative cross-peaks with respect to diagonal), eliminating known problems of NOEs vanishing or spin diffusion, depending on correlation time, when high field spectrometers are used for measurements of medium-size compounds. 

The third block in Fig. 2.1 shows the various possible sensing modes. The basic operation mode of a micromachined metal-oxide sensor is the measurement of the resistance or impedance [69] of the sensitive layer at constant temperature. A well-known problem of metal-oxide-based sensors is their lack of selectivity. Additional information on the interaction of analyte and sensitive layer may lead to better gas discrimination. Micromachined sensors exhibit a low thermal time constant, which can be used to advantage by applying temperature-modulation techniques. The gas/oxide interaction characteristics and dynamics are observable in the measured sensor resistance. Various temperature modulation methods have been explored. The first method relies on a train of rectangular temperature pulses at variable temperature step heights [70-72]. This method was further developed to find optimized modulation curves [73]. Sinusoidal temperature modulation also has been applied, and the data were evaluated by Fourier transformation [75]. Another idea included the simultaneous measurement of the resistive and calorimetric microhotplate response by additionally monitoring the change in the heater resistance upon gas exposure [74-76]. 

The features of the monoHthic integrated sensor systems have not yet been fully exploited. The almost linear relationship between input reference voltage and microhotplate temperature renders the systems suitable for applying any temperature modulation protocol. Due their compatibility with other CMOS-based chemical sensors the microhotplates can be also combined with, e.g., polymer-based mass sensitive, calorimetric or capacitive sensors. The co-integration with such sensors can help to alleviate problems resulting from cross-sensitivities of tin-oxide based sensors to, e.g., volatile compounds such as hydrocarbons. A well-known problem is the crosssensitivity of tin oxide to humidity or ethanol. The co-integration of a capacitive sensor, which does not show any sensitivity to CO, could help to independently assess humidity changes. 

In this example, it is easy to see that, the dynamics of C is quite independent of the kinetics p, which gives a specific solution to the well known problem of the biomass growth rate ignorance in the bioprocess [66]. It is also verified that the convergence rate cannot be tuned because it depends exclusively on the value of the dilution rate. Indeed, Bastin and Dochain [6] have shown that a condition to guarantee the convergence of the observer is that the dilution rate D must be a persisting input, i.e., that there are two positive constants Cl and C2 such as, at every time t ... 

Grow resistant cultivars where there is a known problem. 

Sometimes surprises occur due to unforeseen factors, but sometimes surprises result from gaps in communication. The process analytical chemist should seek the input of process chemists, engineers, and operators early in the project to maximize the chances of learning about relevant known problems. They should spend time at the plant talking to people very familiar with the process. They should ask a lot of questions, and note and pursue any inconsistencies or gaps in the answers. 

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