Estimating the values of wetlands in riparian communities: a tool for decision-making in planning

In spite of the importance of wetlands to the environment and most especially to the host communities, wetlands are constantly under pressure for conversion to other forms of use by policy makers. The reason for undervaluing the significance of wetlands is possibly due to lack of data on its values for it is not easily measured like other environmental goods. This study therefore adopted the use of Contingent Valuation Method (CVM) to measure the direct use values and non-use values of riparian wetlands to the communities in Lokoja, Nigeria. Four hundred and ninety four (494) households were surveyed in seventeen (17) riparian communities involving a series of focus group discussions and questionnaire administration. Our findings show that both direct use values and non-use values of the wetlands exist and majority of the people were willing to pay for these values. Most of them were also against conversion of the wetlands to other forms of use. The mean estimate of non-use values was however more than that of direct use values. Unfortunately, non-use values are not usually considered in decision making concerning wetlands conversion to other forms of use. The estimates of the values of the wetlands to the local communities as found can be used as a basis for argument by planners for its conservation and not conversion

Uncovering the hidden values of wetlands to local communities

The values of wetlands are generally classified into use values and non-use values. The use values are straightforward andmeasurable values but the non-use values are not so. Hence they are most often neglected and not incorporated in wetlands assessment and conversion to other uses by policy makers. Although the wetlands under review are obviously being used for farming and fishing, we attempted establishing from the local users if they have other forms of values for them. We therefore interviewed four hundred and ninety four (494) wetlands users in seventeen riparian local communities in Lokoja, Nigeria. The result of our findings shows that apart from the direct use of the wetlands, other form of uses, the non-use values exists. Bequest value was however dominant among the identified non-use values. Unfortunately this type of value is not usually considered in decision making patterning to wetlands in local communities. We recommend valuation of both the use and non-use values of wetlands in local communities that are being considered for conversion to other uses. This is suggested because the unseen hidden values of wetlands can be uncovered only in a study of this nature

About some problems regarding IKP-DKP of a 9R planar parallel mechanism

Abstract The paper presents some problems which might occur at different stages of the 9R(3RRR) planar mechanisms study (workspace characterizing, forward and direct kinematics, singularities analysis). At each of this stage, it has been identified certain problem which can occur and that need more attention and effort to be solved. In the paper classical methods, and formulas, known from technical literature, have been used, but occurred situations was depicted detailed and illustrated by graphical representations.</jats:p

The conjugate profile of the circular teeth of a spur gear. Part I: Problem statement

Abstract The paper presents the manner of finding the conjugate profile of a circular tooth of a spur gear. A synthesis of the method of enveloping applied to the cam mechanisms is presented in order to relate it the profile of the spur gears. The main argument of employing cam mechanisms is the possibility of obtaining any follower law of motion using a minimum number of parts- the cam and the follower. In the case of the mechanisms with flat face follower, the cam is obtained as an envelope of successive positions of the follower. The gear mechanisms are a particular case of cam mechanisms. The major requirement imposed to this mechanism is to transmit the rotational motion between two shafts with a constant transmission ratio. From here it results that the profile a geared wheel can be completely identified when there are known the distance between the axes, the transmission ratio and the profile of one of the wheels. The most used curve as tooth flank is the involute of a circle, due to the fact that this curve has as conjugate curve an involute, too. Although the involute profiles are common in most of the technical appliances, there are cases when they cannot satisfy the functional constraints of certain devices. As example, in the mechanical watches technology, large transmission ratios are needed and the gears with small number of teeth are used as routine. But this necessity is better fulfilled by cycloidal profiles than the involute ones. The circular profiles for the spur gear are the oldest gears due to the simple profile. The exact conjugate profile of a circular tooth obtained by enveloping by means of dedicated software is presented.</jats:p

The conjugate profile of the circular teeth of a spur gear. Part II: Problem solution

Abstract The paper aims finding the conjugate profile of a circular profile tooth from a gear mechanism with fixed parallel axes and constant transmission ratio. There are presented three manners of attaining the goal. The first two methods are based on the general methodology of gear wheel toothing by envelope machining presented in the first part of the work, considering elementary mechanisms with fixed axes and then a planetary one. The last method is based on applying the Reuleaux’s fundamental law of gearing and has the advantage of obtaining both the conjugate profile of the gear with circular profile and the line of action which is useful in the study of gearing phenomena.</jats:p

A model of the effect of dry friction on the behaviour of a dynamical system

Abstract A dynamical system with one degree of freedom is modelled in two manners: the first one considers that only the dynamical sliding friction is present and the second considers the presence of both dynamic friction and static friction. It is difficult to apply the model of revealed static friction only for the zero relative velocity. For this reason, an approximate model for the static friction was identified, that accepts that the static friction occurs when the magnitude of relative velocity in contact decreases under a certain value, the critical value. The integration of the equations of motion of the two models reveals that for important values of the relative velocity, the two models estimate the same behaviour of the system. An experimental set-up was used to validate the theoretical results.</jats:p

Analysis of the noise emissions of a common-rail pump before and after an endurance test

Abstract One of the problems of the modern era that we are facing nowadays, besides the pollution caused by fuel burning, is the level of noise pollution in constant growth in agglomerated cities. The main source of noise is the transport sector where the number of passenger cars had dramatically increased in recent years. Most of the vehicles around the world are powered by internal combustion engines equipped with a fuel injection system and a small percentage with an electric one. Researchers have shown that noise pollution affects human health from a psychological and physical point of view. Due to the manufacturing process of high-pressure pumps, some pumps mounted on the engine and running under certain conditions can produce a higher audible noise than the engine. The paper presents an experimental investigation on a high-pressure pump that provides a comparison between the noise level at the beginning of its lifetime and that resulting after an endurance test performed on a special test bench. It has been found that the greatest contributor to noise emissions is the high-pressure pump outlet valve when it opens. To improve the sound quality of the high-pressure pump, it is essential to further develop the outlet valve design and better control over the manufacturing process.</jats:p