**4. Conclusions**

The one-dimensional solid state structures of (**1**) and (**2**) are held together by weak interactions via bridging anions—chlorides and azides, respectively—which are disrupted in solution. Because of the polymeric nature and low symmetry of these materials, the analysis of the magnetic properties has been supported by DFT calculations, suggesting strong antiferromagnetic exchange within Cu3 units and weak ferromagnetic interactions among these units. The predominant antiferromagnetic exchange within the Cu3 units has been unequivocally determined in both cases by the analysis of magnetic susceptibility characteristics. In addition, the operation of an antisymmetric exchange in (**1**) was evident by both magnetometry and EPR spectroscopy. The much weaker inter-Cu3 exchange, ferromagnetic in (**1**) and antiferromagnetic in (**2**), is attributed to the fact that non-magnetic Cu-orbitals are involved at one or both ends. EPR spectroscopy determined the magnitude of dipolar interaction in solid state (**1**), while the possible dipolar interaction between Cu3-units of (**2**) cannot be determined with certainty. The solution EPR spectra of both compounds are clearly distinguished from those in the solid state and are straightforwardly attributed to individual Cu3(μ3-OH) species of (**2**), and to the presence of isolated mononuclear and trinuclear species in the case of (**1**). Two new reports, describing the magnetic susceptibilities and (in one case) the EPR spectrum of polymeric supramolecular assemblies of copper(II) complexes, appeared in the literature recently [61,62].

**Supplementary Materials:** The following are available online at http://www.mdpi.com/2624-8549/2/3/39/s1. Table S1: Crystallographic and refinement data for (**1**) and (**2**). Table S2: Selected interatomic distances (Å) and angles (◦) for (**1**). Table S3: Selected interatomic distances (Å) and angles (◦) for (**2**) Figure S1: ORTEP diagram of (**1**). Figure S2: ORTEP diagram of (**2**). Figure S3: Infrared spectrum of (**2**). Figure S4: Solid-state X-band EPR spectra of (**1**) between 5 and 295 K. Figure S5: Dipolar exchange scheme indicating the symmetry codes of the spins Si (i = 1–4) and the main intermolecular distances of (**1**). The crystallographic data for this paper (CCDC 2005300 and 2005301) can also be obtained free of charge via www.ccdc.cam.ac.uk/data\_request/cif, by emailing<EMAIL_ADDRESS>or by contacting The Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; Fax: +44 1223 336033.

**Author Contributions:** Conceptualization, R.G.R.; formal analysis, L.M., R.H. and A.K.B.; investigation, K.S., L.M., R.H. and A.K.B.; writing—original draft preparation, K.S., L.M., R.H. and A.K.B.; writing—review and editing, L.M., R.H., A.K.B. and R.G.R. All authors have read and agreed to the published version of the manuscript.

**Funding:** Research at FIU was funded partially by the National Science Foundation, grant number CHE-1213683. R.H. acknowledges the financial support from institutional sources of the Department of Inorganic Chemistry, Palacky University in Olomouc, Czech Republic, and from the National Programme of Sustainability I (LO1305) of the Ministry of Education, Youth and Sports of the Czech Republic.

**Acknowledgments:** We thank Philippe Turek for support throughout this study.

**Conflicts of Interest:** The authors declare no conflict of interest.


*1.1.2 Higher efficiency and low light pollution due to directional light*

LED lights with a lower lumen output can replace conventional lamps with a higher output. For example, a 30 W LED street light can often replace an 80 W High Pressure Sodium lamp. The reason for this is directionality. LED street lamps are very directional and the light output is much more than other street lamps. Also there is little or no hot spot under the LED lamp. The light emitted from the LED lamp is directed downwards, spread throughout the entire area it covers. This means that a lower amount of light is needed to properly illuminate the area. This also dramatically reduces glare and light pollution which affects the mood of human beings, navigation in birds and insects, mating behavior in animals and flowering in plants.

as refrigerator lights, cold room lights, offices, industrial plants and better for applications requiring frequent switching on and off lights. These bulbs are shocks and vibrations resistant making them the best choice for places like offshore plat-

The light is easily controllable with intelligent systems. The light can be turned on and off instantly and can be dimmed for added energy savings at dawn, dusk, and also during hours of low traffic. Switching on–off and dimming does not affect

The carbon footprint of LED street lights is smaller than other lights due to lower energy usage. Moreover, LEDs last 4 to 8 times longer than any other bulbs, further reducing the carbon footprint of manufacture over the life time. From another angle, wide range application of LED in a country my give better chance to sale

Because of the directional light, light is carefully distributed exactly where it is meant to go and therefore there is no or little light which is wasted by illuminating the night sky or very low background light contribution. This is a considerable plus

It is worth to mention here that for example LED street lamps with color temperature 3.500–4.200 K are rendering more natural light than the yellow of sodium lamps or green of fluorescent streetlights. Also no UV or IR radiation is emitted from the LED street lamps. Color rendering index (CRI) is high (80–90) and displays natural colors of illuminated objects. This reflect actual color of the

LED luminaires contain no harmful substances, like mercury, lead or other hazardous chemical and gasses. Spent LED lamps can be thrown away without any special handling or disposal requirement, since they are recyclable and environmentally friendly. Other lighting bulbs often have hazardous materials such as lead and mercury which require special handling and waste management procedures

European Commission issued the Regulations EC No. 245/2009 for tertiary lighting products on 18 March 2009. On the basis of these Regulations, about 1 billion lighting products have to be replaced by LED type by the year 2015 only in the area of the EU, which translates to 100 million street lamps for street lighting

forms, oil refineries, steel factors, skids and similar applications.

*Economic Applications for LED Lights in Industrial Sectors*

*DOI: http://dx.doi.org/10.5772/intechopen.95412*

the life-time of the luminaire as in the case of fluorescent lights.

there international quota in CO2 emission to other countries.

especially if the local community has a Dark-sky Initiative.

*1.1.9 Free of harmful substances and lower environmental impact*

and industry. The remaining 900 million refer to neon lamps.

which have both economic and environmental costs.

**1.2 International and National Directives**

*1.1.8 Natural light specter: Color rendering index*

*1.1.5 Easily controllable*

*1.1.6 Reducing carbon footprint*

*1.1.7 Dark-sky friendly*

objects.

**23**

#### *1.1.3 Long life: up to 100.000 hours*

LED lights last much longer than conventional lamps (4 to 8 times longer). This result in less expense in replacing the lights themselves but also the labor to replace the lamp is needed less often. This provides a great cost savings by itself.

Also the loss of brightness or lumen depreciation is slower over the life of an LED lamp than that of sodium or other lamp. So not only does the LED have a longer life span than the conventional lamp, but it stays brighter longer than other lamps. The long life span reduces maintenance expenses and makes these bulbs particularly suitable for difficult to reach locations and for streetlights where maintenance costs can be significant.

Lifetime and Lumen maintenance compression between LED and HID lights is illustrated in **Figure** 1. The comparison shows that relamping of HID fixture is required to be done 5 times to achieved one base life time of LED, considering the relamping is required when the Lumen reduces to 70% of initial lamp Lumen [1].

#### *1.1.4 Great operating characteristics*

LED operates at efficiently at low and high temperatures, and unaffected by on/ off cycling. This makes them safer and efficient in special indoor applications such

**Figure 1.** *Lifetime and lumen maintenance compression between LED and HID.*

### *Economic Applications for LED Lights in Industrial Sectors DOI: http://dx.doi.org/10.5772/intechopen.95412*

as refrigerator lights, cold room lights, offices, industrial plants and better for applications requiring frequent switching on and off lights. These bulbs are shocks and vibrations resistant making them the best choice for places like offshore platforms, oil refineries, steel factors, skids and similar applications.


*2.4. Gust Model*

Different gust shapes and intensities were imposed to impact one of the three blades. In order to investigate the worst-case scenario, the gusts were chosen to collide on the blade when the blade pointed upward (i.e., at a 90◦ azimuth angle); in this position, the blade was attacked by the highest wind speed, and therefore, the solicitations acting on it were also the highest. In this work, as in other works on wind gusts [29,44], the gusts were modelled as a local streamwise velocity increase to be superimposed on the local wind velocity field. Using *vg* to indicate the gust's additional velocity and *v* the local wind velocity, the velocity in "gusted" conditions *v* can be expressed as:

$$
v' = \upsilon + v\_{\mathcal{K}}.\tag{6}$$

Notice that, at each time instant, all these velocities are functions of the position in the numerical domain. In order to minimize the computational time and numerical dissipation of the gusts [29,44], the gusts were added in the proximity of the turbine when the blade to be hit was positioned at a 60◦

azimuth angle, namely 30◦ and 20 time steps in advance with respect to the impact of the gust on the blade. They affected only a cylindrical region of 25 m in diameter (i.e., half of the blade span) and 12 m in length, whose axis was aligned with the wind direction. The frontal tip of this cylindrical region was positioned at an appropriate axial coordinate (approximately 1 m downstream of the blade tip's axial coordinate) in order to ensure the gust hit the targeted blade. This means that only in this cylindrical region, the gust velocity used in Equation (6) could be written as:

$$
\upsilon\_{\mathcal{S}} = s(a) \cdot f(r) \cdot A\_{\mathcal{S}} \; \neq \; 0. \tag{7}
$$

In Equation (7), *s* and *f* are shape functions of the gust, depending respectively on the axial (*a*) and radial (*r*) coordinates inside the gusted cylindrical region. In particular, the function *s* sinusoidally ramped up from 0 to 1 in the first 3 m of the axial length of the cylinder, was kept constant and equal to 1 in the middle, and then sinusoidally ramped down from 1 to 0 in the last 3 m of the axial length. Figure 4 illustrates the initial position and shape of the imposed gusts, as well as the coordinates *a* and *r*.

**Figure 4.** (**left**) Side view with detail of the blade tip axial position relative to the gusted region and (**right**) front view of the initial position and shape of the imposed gusts (in red) with respect to the wind turbine.

For what concerns the gust amplitude *Ag*, probabilistic analyses of wind gusts have shown that a gust amplitude of 5 m/s has more than an 80% probability of daily occurrence over central Europe when the wind conditions are similar to the ones chosen in this work [45]. Similarly, gusts exceeding this speed are commonly reported in Germany [46]. Also, more intense gusts (18 to 25 m/s) are fairly common in Europe, especially in coastal areas [25,47]. For these reasons, two gust amplitudes *Ag* were used in this work, namely 5 and 10 m/s.

Lastly, two shape functions *f* were used in this work. In the first subsection, a novel gust shape function was proposed, imposing a local redistribution of the flow rate and no global change in it, providing a velocity deficit on its border and a velocity increase in its center. This gust shape was conceptually similar to the "extreme operating gust" from the 61400-IEC standards for wind turbines. Subsequently, in the second subsection, a consistently positive gust velocity was used, analogous to the "extreme coherent gust" from the 61400-IEC standards for wind turbines.