**Author details**

© 2021 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

*Stochastic versus Ray Tracing Wireless Channel Modeling for 5G and V2X Applications… DOI: http://dx.doi.org/10.5772/intechopen.101625*


6. Combustor diffuser nozzle sections

A dual mode scramjet configuration, as presented in Figure 30, in addition to having a fore-section consisting of a forebody, inlet, isolator sections; also has an aft-section consisting of a combustor, diffuser and nozzle sections. Whilst the focus of this chapter has been on the design of the fore-section, a brief discussion on the design of the aft-section and its integration is warranted for the sake of completion in the design of the dual mode scramjet.

Design of the aft-section focuses on four fundamental design sections; a transition section, a combustor section, a diffuser section and a nozzle section, Figures 31 and 32. The transition section, as implied in the name, is designed to prepare the

flow before it enters the combustor. This section takes the flow leaving the isolator duct and guides it towards combustor. The primary design goal is to ensure that the flow entering the combustor is as organized as possible. The combustion section is where fuel is added, mixed and burned. The diffuser section is used to help control the combustion process as the scramjet operates across its dual mode, that is, switching from ramjet mode to scramjet mode. The nozzle section is used to accel-

A completed scramjet flow-path can now be obtained with the assembly of both

the forebody-inlet-isolator and combustor-nozzle sections. Two samples are presented in Figures 33 and 34. Figure 33 presents a scramjet that has a square combustor configuration and Figure 34, a circular combustor configuration. Referring back to Figure 2(c), one can observe that a variety of geometries can be

erate the exhaust gases as the flow leaves the dual mode scramjet.

7. Scramjet flow-path

Illustration of the transition-combustor-nozzle element.

Inversely Designed Scramjet Flow-Path DOI: http://dx.doi.org/10.5772/intechopen.85697

Figure 32.

Figure 33.

Figure 34.

71

4-pts scramjet with square combustor C-sections.

4-pts scramjet with circular combustor C-sections.

Figure 30.

A dual mode ramjet-to-scramjet concept [1].

Figure 31.

2D-3D geometric construction from prescribes isolator cross-section and aerodynamic inputs [1].

Inversely Designed Scramjet Flow-Path DOI: http://dx.doi.org/10.5772/intechopen.85697

A similar process was implemented with AVUS and 2-D slices of flow-field data are extracted and presented in Figures 25–29. On examining these 2-D slices of 3-D data, it is observed that the stream tube is processing the flow in an organized consistent manner that is aligned with its design. Of note are Figures 27–29. Figure 27 examines the z-component of the velocity, and indicated that there is very little cross-flow. Arguable, this is an Euler analysis, however it is worth pointing out that the stream tube 2-D design process holds. This is further supported by Figures 28 and 29 which presents data on the Mach and pressure

A dual mode scramjet configuration, as presented in Figure 30, in addition to having a fore-section consisting of a forebody, inlet, isolator sections; also has an aft-section consisting of a combustor, diffuser and nozzle sections. Whilst the focus of this chapter has been on the design of the fore-section, a brief discussion on the design of the aft-section and its integration is warranted for the sake of completion

Design of the aft-section focuses on four fundamental design sections; a transition section, a combustor section, a diffuser section and a nozzle section, Figures 31 and 32. The transition section, as implied in the name, is designed to prepare the

2D-3D geometric construction from prescribes isolator cross-section and aerodynamic inputs [1].

distribution at the isolator exit.

6. Combustor diffuser nozzle sections

Hypersonic Vehicles - Past, Present and Future Developments

in the design of the dual mode scramjet.

A dual mode ramjet-to-scramjet concept [1].

Figure 30.

Figure 31.

70

Figure 32. Illustration of the transition-combustor-nozzle element.

flow before it enters the combustor. This section takes the flow leaving the isolator duct and guides it towards combustor. The primary design goal is to ensure that the flow entering the combustor is as organized as possible. The combustion section is where fuel is added, mixed and burned. The diffuser section is used to help control the combustion process as the scramjet operates across its dual mode, that is, switching from ramjet mode to scramjet mode. The nozzle section is used to accelerate the exhaust gases as the flow leaves the dual mode scramjet.


**Citation:** Zhang, W.; Xu, K.; Long, W.; Zhou, X. Microstructure and Compressive Properties of Porous 2024Al-Al3Zr Composites. *Metals* **2022**, *12*, 2017. https://doi.org/ 10.3390/met12122017

Academic Editors: Noé Cheung and Matej Vesenjak

Received: 13 September 2022 Accepted: 22 November 2022 Published: 24 November 2022

**Publisher's Note:** MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

**Copyright:** © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).


**3.1. Pirin**

measured in cases of changeable lower ends, again with the use of a tape. Current positions of firn level can be marked with paint on the rock. Measured data are then processed in a laboratory: measured lines are entered in Geographic Information System (GIS) in an appropriate scale, and then, the software calculates the exact areas. When only selected lengths and widths are measured, they are entered in the software in a proper scale. They are used as a frame, on which photographs of the glacier surface, made from distant positions, are then fitted. After that glacier contour from those images is digitized, and the area is calculated.

Spatial overlay of data from multiple measurements allows for precise comparison between glacier states of different years. Repetitive photography is also an important technique to obtain inter-annual changes. Glaciers are photographed each time from same (fixed) positions, and then images are overlayed. Precise data about area and volume cannot be obtained by using this method, but it is highly indicative when tracing the relative changes and trends in the development of small glaciers. Later, if proper scaling is done on the field, accurate absolute values for surface area and level variations can be retrieved from such

The current state of snow and firn cover is also quite indicative for the mass balance from the past year, especially for the evaluation of accumulation and ablation varieties across glacier surface. It is assessed on the field, with the use of alpine equipment (crampons, ice axe, etc.). Effects from accumulation season only are studied in spring (April–May) by measuring snow cover thickness and density in glacier vicinities. Such observations have been rare, especially in our region, due to the high avalanche danger and limited accessibility of glacier sites in that

Morphology studies involve geomorphological, glaciological and geophysical methods. Morphology analysis aims to reveal how a glacier is formed. It requires a detailed description of glacier surface geometry (contours, tilts, bergschrund, crevasses, caverns) and the character of surrounding landforms (moraines, protalus ramparts, avalanche gullies, screes). Size and roundness and lichen cover of debris are assessed. Weathering of depositional forms can be examined, e.g. with a Schmidt hammer [21, 22]. However, only relative age can be assessed

Internal structure of small glaciers is testified with various techniques, which require investments in labour and equipment. The easier way is to excavate pits in glacier body, but this is hard to do and not much informative as pits cannot be deep. It is better to study natural outcrops of glacier body instead (bergschrund or cracks). Drilling with appropriate ice drills allows to reach depths below 10 m and to retrieve unspoiled cores for analysis in a laboratory. Radar sounding makes possible to estimate underground structure (thickness, sediment layers, patches of buried ice) without digging [23]. Both drilling and sounding, however, require carrying out heavy and expensive equipment, and this sets limitations on the application of

Isotope composition of firn and ice along with absolute ages of formation of glaciers and their surrounding landforms (e.g. moraines) can be verified with the use of laboratory techniques after taking samples of rock, ice or organic particles. Such analyses (isotope, radiocarbon, etc.) are costly and have been applied just for two of the small glaciers on the Balkan Peninsula

these techniques, especially in hardly accessible high mountain areas.

photographs.

80 Glacier Evolution in a Changing World

time of the year.

with these methods.

Pirin is the second highest mountain in Bulgaria and the third highest on the Balkans (**Figure 2**). It rises in the south-west part of the country, reaching an altitude of 2914 m a. s. l. at its highest point—Mt. Vihren. The mountain is a horst block, oriented NNW to SSE, which is built of granitic intrusions and a mantle of metamorphic rocks. A section of the northern part has on its top a thick (500–1000 m) cover of marble that composes the main ridge and the northern slope. Several gigantic glacial depressions (cirques) were formed in this area during the Wuermian ice age and subsequently have been karstified. At least four sustainable snow/firn features have been discovered and mapped in this area. Two of them have been proved to be small glaciers and, more strictly, glacierets [3, 5, 7].

Snezhnika glacieret is located at 41°46′09″N and 23°24′10″E at 2400–2450 m altitude a. s. l., just below the north-eastern marble wall of Vihren peak. The glacieret has an eastern exposure and a trapezoid shape with length of 80–100 m and width about 90 m. About 4–5 high moraine ridge surrounds glacieret body from three sides. It is considered to be formed in its present shape in the Little Ice Age [4–6] (**Figure 3**).

The first measurements and drilling of Snezhnika were done in 1957–61 by the Bulgarian karstologist Vladimir Popov, in relation to the Third International Geophysical Year [26]. The drilling reached the bottom at 8-m depth. Regular climatic measurements were performed in a meteorology station, which was equipped with a thermograph and gauge for total precipitation [27]. After the end of the programme, research was abandoned. German scientists from Dresden measured glacieret area in the autumns of 1994, 1996 and 1998–2007. In 2006, they made three drillings of the firn, the deepest reaching the bottom at 11 m. Glacier ice with a density of 0.9 Kg/l was found in the cores at depths below 10 m, and the radiocarbon dating of organic particles from these depths confirmed the ice was at least 100 years old [4–6]. This is a direct evidence for the glacial nature of Snezhnika. Since 2008, the glacieret has been also monitored by Bulgarian scientists. Its area has been measured in every autumn for the last years (2008–2016) [3, 19, 20]. After the hot summer of 2012, a cave that is 25 m long and 1.5–2.5 high opened at the bottom, reaching the back wall. There, we observed a cross-section of the glacieret body with sediment strata inside the firn [28]. While going downwards from the highest end (at the bergschrund), those layers changed their tilt from normal to reverse, indicating the presence of slow curvy digging motion, typical for the accumulation zone of mountain glaciers [3, 23].

**Figure 2.** Glacierets and snow patches in Pirin mountains.

In these last 23 years, the area was subjected to large fluctuations, between 0.30 and 0.77 ha, without any specific trend. Average area for the period is 0.55 ha. At present, Snezhnika has been recognized as the southernmost glacial mass of Europe, being, together with Banski suhodol, the other glacieret in Pirin, the only one that is situated in south of the parallel 42°N [2].

Banski suhodol glacieret is situated 1.5 km to the north of Snezhnika, in a vast cirque below the second highest peak in Pirin, Kutelo (2908 m). It has a northerly orientation, irregular shape and an area about 1.2 ha [3, 7, 8]. The altitude of the glacieret is 2610–2700 m. It has a complicated shape, with a length 120–130 m and width 130–135 m. The surface is concave, tilted between 25 and 40°. Two moraine ridges parallel to each other are observed below glacieret front. They are more pronounced in the middle and less on the sides, as avalanche and debris flow paths pass there.

Being hardly accessible, this feature was described and mapped for the first time in 2009 [7, 8] and has been monitored annually since then [3]. Since 2011, the fluctuations of glacieret front have been measured in relation to five fixed points placed on large boulders. The inter-annual fluctuations of the surface of Banski suhodol glacieret are weakly expressed, with a maximum registered in 2010 and minimum in 2012. In October 2012, fresh glacial striations were observed on bedrock surfaces at glacieret front: a direct evidence for glacial type motion of the firn-ice mass of the glacieret.

Apart from the glaciers, two sustainable snow patches are also situated in Banski suhodol cirque. They have been found persistent for the last 8 years, but the low tilts and the closed

**Figure 3.** Snezhnika and Banski suhodol glacierets in Pirin.

In these last 23 years, the area was subjected to large fluctuations, between 0.30 and 0.77 ha, without any specific trend. Average area for the period is 0.55 ha. At present, Snezhnika has been recognized as the southernmost glacial mass of Europe, being, together with Banski suhodol,

Banski suhodol glacieret is situated 1.5 km to the north of Snezhnika, in a vast cirque below the second highest peak in Pirin, Kutelo (2908 m). It has a northerly orientation, irregular shape and an area about 1.2 ha [3, 7, 8]. The altitude of the glacieret is 2610–2700 m. It has a complicated shape, with a length 120–130 m and width 130–135 m. The surface is concave, tilted between 25 and 40°. Two moraine ridges parallel to each other are observed below glacieret front. They are more pronounced in the middle and less on the sides, as avalanche and

Being hardly accessible, this feature was described and mapped for the first time in 2009 [7, 8] and has been monitored annually since then [3]. Since 2011, the fluctuations of glacieret front have been measured in relation to five fixed points placed on large boulders. The inter-annual fluctuations of the surface of Banski suhodol glacieret are weakly expressed, with a maximum registered in 2010 and minimum in 2012. In October 2012, fresh glacial striations were observed on bedrock surfaces at glacieret front: a direct evidence for glacial type motion of the

Apart from the glaciers, two sustainable snow patches are also situated in Banski suhodol cirque. They have been found persistent for the last 8 years, but the low tilts and the closed

the other glacieret in Pirin, the only one that is situated in south of the parallel 42°N [2].

debris flow paths pass there.

82 Glacier Evolution in a Changing World

**Figure 2.** Glacierets and snow patches in Pirin mountains.

firn-ice mass of the glacieret.

depressions, where they lie, suggest they can hardly move. Their positions, however, and the moraines that surround them, indicate that they should have been glaciers in the nearly past (maybe in the Little Ice Age).

Presence of a perennial firn and ice was also reported for the cirque Bayuvi dupki, by Hristo Peev in the middle of the twentieth century [29, 30]. He reported about a 500-m long 'firn glacieret' that occupied the bottom of that cirque and gave information about years in which it was greater/smaller for a period of almost 2 decades. Although no figures were given for areas or lengths, this research is considered the first monitoring of a small glacier in Bulgaria. Nowadays, however, no snow remains in this cirque after hot summers. Reports for the existence of sustainable snow patches have been, however, made by enthusiast mountaineers for some locations in the Kamenitica cirque [31].

### **3.2. Durmitor**

Durmitor is located in NW Montenegro. It is the second highest massif in the main Dinaric chain (Mt. Bobotov kuk, 2522 m a. s. l), a very small mountain, situated on a karst plateau at 1450–1550 m a. s. l. close to the deepest canyons of Europe (those of the rivers Tara and Piva [32]). The main part of the mountain is composed of thick Triassic and Jurassic limestones, which to the south overthrust Cretaceous flysch formations [33]. Four vast cirques are heritage from the extensive Wuermian glaciation. In the easternmost of them is the Debeli namet, the only present-day small glacier in Montenegro. The glacier is located on 2030–2200 m altitude; it has a northerly exposure, length about 300–320 m and width 110–135 m [34]. It has a classical elongated contour, with a wider concave upper section and bulged tongue at the front. The glacier is surrounded by a huge moraine, which rises 10–20 m above the surface. An amphitheatre of rocks and couloirs rises more than 300 m to reach the main ridge of the mountain in the south of the glacier: a grassy plateau, at 2400–2450 m a. s. l. (**Figure 4**.). Its lower section represents a surface of barren corroded rocks with a tilt steadier than the rock wall itself. This is the area where Debeli namet expands most, after years, of positive mass balances [9, 34] (in contrast to glacierets in Pirin, which fluctuate mainly in their frontal sections). Tilts of the glacier surface are in the range of 20–25°, reaching 35–40° just at the upper end. Strong mechanical weathering of rocks at the back supplies lots of debris on the ice surface, especially in the SE part.

Debeli namet was recognized as a small glacier by all researchers [2, 3, 9, 13–18]. For the first, it was mentioned in the 1960s [35]. Predrag Djurović from Belgrade, Serbia, measured glacier area in the autumns of 2003, 2006, 2008–2010, and 2015–2016 and reconstructed the size on the basis of aerial photographs for 1961, 1971, and 1981. In 1993, he tried to measure ice velocity with a stick stabbed in the middle part of the glacier. It was found at glacier front after 11 years [18]. Philip Hughes from the UK made size measurements of the glacier in 2003 and 2005–2007 and a lichenometry dating of the surrounding moraine, which addressed its age to the beginning of the twentieth century [13–16]. Accurate surface area measurements of the glacier have been done by Bulgarian scientists every year since 2011 [3]. The ice of the glacier was sampled for heavy metals and radioactive elements [24, 25]. Area observations cover a long period (since 1961) but have become already systematic since 2003. Here, it is also hard to outline any trend in fluctuations that are increasing from year to year (from 1.2 to 3.1 ha, i.e. up to three times). In the last 3 years, however, this glacier has suffered the most dramatic shrinkage on the Balkans. But it is still larger compared to its sizes during the 1990s.

There is one more perennial snow-firn feature in Durmitor, the snow patch in Snežna vrtača, a giant round sinkhole on the plateau of Šlijeme, filled with snow all year round [33].

**Figure 4.** Maps of Durmitor and Debeli namet glacier.

#### **3.3. Prokletije**

areas or lengths, this research is considered the first monitoring of a small glacier in Bulgaria. Nowadays, however, no snow remains in this cirque after hot summers. Reports for the existence of sustainable snow patches have been, however, made by enthusiast mountaineers for

Durmitor is located in NW Montenegro. It is the second highest massif in the main Dinaric chain (Mt. Bobotov kuk, 2522 m a. s. l), a very small mountain, situated on a karst plateau at 1450–1550 m a. s. l. close to the deepest canyons of Europe (those of the rivers Tara and Piva [32]). The main part of the mountain is composed of thick Triassic and Jurassic limestones, which to the south overthrust Cretaceous flysch formations [33]. Four vast cirques are heritage from the extensive Wuermian glaciation. In the easternmost of them is the Debeli namet, the only present-day small glacier in Montenegro. The glacier is located on 2030–2200 m altitude; it has a northerly exposure, length about 300–320 m and width 110–135 m [34]. It has a classical elongated contour, with a wider concave upper section and bulged tongue at the front. The glacier is surrounded by a huge moraine, which rises 10–20 m above the surface. An amphitheatre of rocks and couloirs rises more than 300 m to reach the main ridge of the mountain in the south of the glacier: a grassy plateau, at 2400–2450 m a. s. l. (**Figure 4**.). Its lower section represents a surface of barren corroded rocks with a tilt steadier than the rock wall itself. This is the area where Debeli namet expands most, after years, of positive mass balances [9, 34] (in contrast to glacierets in Pirin, which fluctuate mainly in their frontal sections). Tilts of the glacier surface are in the range of 20–25°, reaching 35–40° just at the upper end. Strong mechanical weathering of rocks at the back supplies lots of debris on the ice surface,

Debeli namet was recognized as a small glacier by all researchers [2, 3, 9, 13–18]. For the first, it was mentioned in the 1960s [35]. Predrag Djurović from Belgrade, Serbia, measured glacier area in the autumns of 2003, 2006, 2008–2010, and 2015–2016 and reconstructed the size on the basis of aerial photographs for 1961, 1971, and 1981. In 1993, he tried to measure ice velocity with a stick stabbed in the middle part of the glacier. It was found at glacier front after 11 years [18]. Philip Hughes from the UK made size measurements of the glacier in 2003 and 2005–2007 and a lichenometry dating of the surrounding moraine, which addressed its age to the beginning of the twentieth century [13–16]. Accurate surface area measurements of the glacier have been done by Bulgarian scientists every year since 2011 [3]. The ice of the glacier was sampled for heavy metals and radioactive elements [24, 25]. Area observations cover a long period (since 1961) but have become already systematic since 2003. Here, it is also hard to outline any trend in fluctuations that are increasing from year to year (from 1.2 to 3.1 ha, i.e. up to three times). In the last 3 years, however, this glacier has suffered the most dramatic shrinkage on the Balkans. But it is still larger compared to its

There is one more perennial snow-firn feature in Durmitor, the snow patch in Snežna vrtača,

a giant round sinkhole on the plateau of Šlijeme, filled with snow all year round [33].

some locations in the Kamenitica cirque [31].

**3.2. Durmitor**

84 Glacier Evolution in a Changing World

especially in the SE part.

sizes during the 1990s.

Prokletije is a large mountain system, situated mainly in the northern Albania, on the borders with Montenegro and Kosovo. It marks the SE conclusion of the main Dinaric chain. Strongly dissected by deep valleys, it rises to almost 2700 m a. s. l. (Mt. Jezerce, the highest of all Dinarides). The central, southern and western sections of the mountain are made of Mesozoic limestone: very thick, tectonically reworked, heavily exerted by Wuermian glaciers and deeply karstified. The present rugged morphology of the mountain reminds of the Dolomites in Italy. In the eastern flanks of the mountain system, silicate rocks prevail and the topography there is smoother and relict glacial relief is much less pronounced (**Figure 5**).

Prokletije is among the least explored mountains in Europe. First, the famous Serbian geographer Jovan Cvijić paid attention to the impressive topography, left from the Pleistocene glaciers in the area around of Plav lake [36]. The presence of perennial snow and ice in the area around the highest point Maja e Jezrecës (Jezerce, 2694 m a. s. l.) was first mentioned by an Austrian topographer, who investigated the area during WWI, and mentioned snow fields more than

**Figure 5.** Prokletije mountain with locations of small glaciers.

1 km long [37]. Until the beginning of the twenty first century, geographical studies for this area were very few and not focused on present glaciation (e.g. [38, 39]). In 2007–2008, the area around Mt. Jezerce was researched for relict and present glacial evidence by Serbian geomorphologists, who reported about three 'active glaciers': the largest on the Balkan Peninsula with an area of 5 ha in the cirque Buni i Jezerces at 1980–2100 m a. s. l. and two smaller glaciers to the NE of the highest peak [12]. Soon after, another glacier with an area of 4.9 ha was described by a British expedition to lie under the eastern wall of Mt. Jezerce [15]. Since 2011 the area has been visited by Bulgarian scientists every autumn. As a result, it was revealed that the mentioned feature in the cirque Buni i Jezerces is in fact a snow patch, as it melted almost completely in 2012 and again in 2016. To compensate that, two more small glaciers were declared in the upper part of the same cirque on the basis of morphology. Bulgarian scientists have made several expeditions in other ranges within the carbonate area of Prokletije. In result, a total of 13 suggestible glaciers have been recorded and mapped in four main locations in this range, on altitudes between 2450 and 1910 m a. s. l. [3], but the presence of more is likely as many branches of this extensive mountain system are still unresearched. For the last 6 years, changes in the size of the glaciers and snow patches in the area around Mt. Jezerce have been studied in detail [3, 9–11]. The largest of them, the glacieret Jezerce III, has had an average area of 4.5 ha. Large fluctuation of the firn bodies in terms of surface area was recorded in 2011–2016, with a considerable shrinkage in the years after 2013. However, the observed thickness of some of these small glaciers (15 m and more) indicates that they are still far from complete melt.

#### *3.3.1. Popluk range*

Popluk is named the highest part of Prokletije system [38]. It includes Maja e Jezerces peak and the surrounding ridges, separated from the adjacent ranges with clearly defined cols. To the south, Valbona pass (1709 m a. s. l.) makes the transition to the high Hekurave range (2625 m a. s. l.); to the NE is the Qafa Valbona saddle (2030 m), the pass to Bielić range (Maja e Rosit, 2524 m); to the West is the low Peja Pass (Qafa Pejes, 1690 m) that separates the valleys of Theth and Ropojana and the ranges Popluk and Karanfili. Popluk Mt. Jezerce is surrounded from three sides by large deep cirques: Buni i Jezerces (to the NW), Llugu i Zajave (to the E) and Buni i Gropavet (to the SW) (**Figure 6**).

Llugi i Zajave cirque hosts three small glaciers (glacierets). They are not situated on the bottom of the cirque but on a high terrace just under the 200–300 m high NE rock wall of Mt. Jezerce. Jezerce I (1.2 ha) and Jezerce II (2 ha), located to the NW of the summit point, are typical glacierets: they contact the rock wall, have straight surface and widths larger than lengths. Their fronts, which lie on deeply weathered and corroded limestone blocks, are bordered by moraine ridges several metres high. When they expand, both glaciers join into a single snow field. In periods of retreat Jezerce II disintegrates into several parts. The glacieret Jezerce III is situated further to the SE. It lies on a wide terrace on two levels (at 2400–2450 and 2350–2370 m,

1 km long [37]. Until the beginning of the twenty first century, geographical studies for this area were very few and not focused on present glaciation (e.g. [38, 39]). In 2007–2008, the area around Mt. Jezerce was researched for relict and present glacial evidence by Serbian geomorphologists, who reported about three 'active glaciers': the largest on the Balkan Peninsula with an area of 5 ha in the cirque Buni i Jezerces at 1980–2100 m a. s. l. and two smaller glaciers to the NE of the highest peak [12]. Soon after, another glacier with an area of 4.9 ha was described by a British expedition to lie under the eastern wall of Mt. Jezerce [15]. Since 2011 the area has been visited by Bulgarian scientists every autumn. As a result, it was revealed that the mentioned feature in the cirque Buni i Jezerces is in fact a snow patch, as it melted almost completely in 2012 and again in 2016. To compensate that, two more small glaciers were declared in the upper part of the same cirque on the basis of morphology. Bulgarian scientists have made several expeditions in other ranges within the carbonate area of Prokletije. In result, a total of 13 suggestible glaciers have been recorded and mapped in four main locations in this range, on altitudes between 2450 and 1910 m a. s. l. [3], but the presence of more is likely as many branches of this extensive mountain system are still unresearched. For the last 6 years, changes in the size of the glaciers and snow patches in the area around Mt. Jezerce have been studied in detail [3, 9–11]. The largest of them, the glacieret Jezerce III, has had an average area of 4.5 ha. Large fluctuation of the firn bodies in terms of surface area was recorded in 2011–2016, with a considerable shrinkage in the years after 2013. However, the observed thickness of some of these small glaciers (15 m and more) indicates that they are still far from complete melt.

**Figure 5.** Prokletije mountain with locations of small glaciers.

86 Glacier Evolution in a Changing World

Popluk is named the highest part of Prokletije system [38]. It includes Maja e Jezerces peak and the surrounding ridges, separated from the adjacent ranges with clearly defined cols. To the south, Valbona pass (1709 m a. s. l.) makes the transition to the high Hekurave range

*3.3.1. Popluk range*

**Figure 6.** Small glaciers and snow patches in Popluk range.

respectively). However, the firn mass does not actually move down: it is mostly concentrated on the upper level (to the NW), which is on a shadier position, just below the peak. At the time of positive mass balance, all depression is filled with snow, and the glacieret obtains an impressive size (5–7 ha). Jezerce III is the largest small glacier on the Balkan Peninsula. After hot and dry years, ice masses on the lower level defragment to several snow patches occupy sinkhole bottoms, and the glacier becomes limited on the upper level. However, even in such conditions, it remains larger than the others, and ice thickness is still more than 10 m. In October 2014, surfaces of polished rock were observed by us near the firn front to evidence glacial type motion.

Buni i Jezerces is the largest of the three cirques. It is divided into two parts [12]. The lower part is wider oriented to the north. On its grassy bottom, at altitudes between 1750 and 1800 m, there is a group of six glacial karst lakes. Snow and ice features are located mostly in the upper section of the large cirque, which is narrower and oriented to WNW, with altitudes of the bottom between 2000 and 2250 m. Here, glaciers do not lie in the bottom as well but also in deep depressions on a cirque shoulder on 2400–2480 m a. l. The glacieret Jezerce IV (1.8 ha) is in a rocky depression, carved in the NW wall of Mt. Jezerce. It has an irregular shape with length of 270 m and width 70–80 m. The solid rock around produces small quantity of creep material, and in consequence, the two moraines that surround the lower end are tiny. Jezerce V lies further to the west, on the passage between Mt. Jezerce and its western neighbour Maja Malisores (2508 m). It has northern exposure and a pear-like shape of a small cirque glacier, with round upper part and narrow elongated snout. The glacier is situated in a zone of weak rocks, considerable amounts of pebble are produced especially on the SW side, and debris products are deposited as a high moraine ridge on the NW side of the tongue. To the NE of glacier end lies a rock wall, so moraine material is lacking there, and moraines at the very front of the glacier are small, as this area should serve as an avalanche track.

Several sustainable snow patches are found to be spread on the main bottom of the cirque's upper section. Ginko snow patches are in the middle part, at 2100 m a. s. l. They fill bottoms of two sinkholes, lying on a thick cover of scree material. Through years, the snow level can vary by 5–6 m and the area from 0.4 to 4 ha. When the level is high, all patches join in a single one. At the outlet of the upper section is the Koljaet snow patch, which was considered by previous researchers the largest glacier on the Balkans. And indeed, the large snow extent observed in some autumns (up to 4.5 ha for example in 2006 and 2013) and the high moraine ridges at the front can give impression of a small glacier. But regular observations have showed that in other years, the snow was actually missing there. In the small cirque to the North of Maja e Kohervhakes peak, there is another elongated snow field with NW aspect and length reaching more than 200 m in the autumns of some years (e.g. 2013). However, it was completely melted after the summer of 2016, so it is categorized as a snow patch.

The third large cirque, Buni i Gropavet, hosts several snow patches, none of them is considered permanent in long-term sense [12].

#### *3.3.2. Hekurave range*

This impressive and long range is situated to the south of Valbona valley from its beginning to its end, but the highest part lies to the west of Hekurave peak. This range has a west-east orientation and culminates in the peak Maja Gryk e Hapt (2625 m a. s. l., the third highest in Prokletije). The northern slope is very steep and rocky, and in many regions, it rises almost vertically from Valbona valley.

respectively). However, the firn mass does not actually move down: it is mostly concentrated on the upper level (to the NW), which is on a shadier position, just below the peak. At the time of positive mass balance, all depression is filled with snow, and the glacieret obtains an impressive size (5–7 ha). Jezerce III is the largest small glacier on the Balkan Peninsula. After hot and dry years, ice masses on the lower level defragment to several snow patches occupy sinkhole bottoms, and the glacier becomes limited on the upper level. However, even in such conditions, it remains larger than the others, and ice thickness is still more than 10 m. In October 2014, surfaces of polished rock were observed by us near the firn front to evidence glacial type motion. Buni i Jezerces is the largest of the three cirques. It is divided into two parts [12]. The lower part is wider oriented to the north. On its grassy bottom, at altitudes between 1750 and 1800 m, there is a group of six glacial karst lakes. Snow and ice features are located mostly in the upper section of the large cirque, which is narrower and oriented to WNW, with altitudes of the bottom between 2000 and 2250 m. Here, glaciers do not lie in the bottom as well but also in deep depressions on a cirque shoulder on 2400–2480 m a. l. The glacieret Jezerce IV (1.8 ha) is in a rocky depression, carved in the NW wall of Mt. Jezerce. It has an irregular shape with length of 270 m and width 70–80 m. The solid rock around produces small quantity of creep material, and in consequence, the two moraines that surround the lower end are tiny. Jezerce V lies further to the west, on the passage between Mt. Jezerce and its western neighbour Maja Malisores (2508 m). It has northern exposure and a pear-like shape of a small cirque glacier, with round upper part and narrow elongated snout. The glacier is situated in a zone of weak rocks, considerable amounts of pebble are produced especially on the SW side, and debris products are deposited as a high moraine ridge on the NW side of the tongue. To the NE of glacier end lies a rock wall, so moraine material is lacking there, and moraines at the very front of the glacier

Several sustainable snow patches are found to be spread on the main bottom of the cirque's upper section. Ginko snow patches are in the middle part, at 2100 m a. s. l. They fill bottoms of two sinkholes, lying on a thick cover of scree material. Through years, the snow level can vary by 5–6 m and the area from 0.4 to 4 ha. When the level is high, all patches join in a single one. At the outlet of the upper section is the Koljaet snow patch, which was considered by previous researchers the largest glacier on the Balkans. And indeed, the large snow extent observed in some autumns (up to 4.5 ha for example in 2006 and 2013) and the high moraine ridges at the front can give impression of a small glacier. But regular observations have showed that in other years, the snow was actually missing there. In the small cirque to the North of Maja e Kohervhakes peak, there is another elongated snow field with NW aspect and length reaching more than 200 m in the autumns of some years (e.g. 2013). However, it was completely melted

The third large cirque, Buni i Gropavet, hosts several snow patches, none of them is consid-

This impressive and long range is situated to the south of Valbona valley from its beginning to its end, but the highest part lies to the west of Hekurave peak. This range has a west-east orientation and culminates in the peak Maja Gryk e Hapt (2625 m a. s. l., the third highest in

are small, as this area should serve as an avalanche track.

after the summer of 2016, so it is categorized as a snow patch.

ered permanent in long-term sense [12].

*3.3.2. Hekurave range*

88 Glacier Evolution in a Changing World

Up to now, five small glaciers have been discovered in this range [3] (**Figure 7**). Three of them are on a wide terrace in the middle section of the northern slope. The big Glacieret lies at the end of the terrace, in a wide tilted couloir below the northern rock face of Maja e Zhapores (2529 m). It has a trapezoid shape and is bordered by a huge moraine. Next to the east is the Mertur glacier, a small cirque glacier of a classical shape (area around 2 ha), the most representative in Prokletije. It is situated at 2350–2450 m a. s. l. in a zone of weakened rocks

**Figure 7.** Small glaciers and snow patches in Hekurave range.

(limestone-marble breccia) that cross the ridge in a transverse direction. The scree behind the glacier produces large amounts of debris, which are piled up at the front as a high crescent shaped moraine. Despite that glacier surface is white and clean even after dry summers which indicates the good condition of the glacier and the active recent motion in it. A complex of three fresh stadial moraines is spread down to 500 m from the glacier, indicating its much larger size in the near past. Still further to the NE is the Brjasit small glacier (front at 2280–2300 m a. s. l.), an elongated body of firn and ice (2.5–3 ha), surrounded by moraines from three sides.  Further, another firn feature is found in the East. In September 2015, it was all covered by debris. It is obvious that there is buried ice inside, but despite the huge moraine formed behind the front, we accept this feature as a snow patch because of the lack of signs of recent activity.

At least two more small glaciers exist in this mountain range. One of them, Upper Zhapor glacier, occupies a high hanging cirque at 2300–2350 m a. s. l. near Zhapores peak. The glacier has a triangular shape, dictated by the topography of its bed, and in 2015, its surface was relatively fresh, with cracks in the lower part reaching 6–7 m depth. A short moraine made of huge blocks separates glacier end from the beginning of a steep couloir, which descends down to the valley of Valbona. The other feature, Stamenov glacier, lies in an easterly oriented cirque to the East of Maja Gryk e Hapt. It has an elongated shape, a clearly visible moraine that surrounds it from three sides and a relatively fresh look on all images taken in autumn.

#### *3.3.3. Kolata range*

This prominent part of Prokletije mountain system lies to the NE of Bjelić range, and is connected to it through the pass Qafa e Presljopit (2039 m a. s. l.). Rising sharply between the valleys of Valbona (to the S), Cherem (a tributary of Valbona, to the N and E) and Zarunica (tributary of Vruja and Lim rivers, to the NW), it is crossed by the Albanian-Montenegrin border and hosts the highest peaks of all Montenegro: Zla Kolata (2534 m a. s. l.) and Dobra Kolata (2528 m). The top of the range is a flattened plateau of flysch rocks, at the eastern end of which rises the highest point Ravna Kolata (2556 m), entirely in Albania. The plateau ends with almost vertical limestone cliffs from all sides. Western and southern slopes are very steep in all their height, descending almost 2 km down to the surrounding valleys. The northern and eastern slopes have staircase profiles. There are several deep and relatively narrow cirques, carved to the north of the plateau surface (**Figure 8**).

Kolata glacieret lies in the deepest cirque with a central position between the three main peaks of this range. The cirque is 200–250 m deep, with vertical walls from three sides, and looks to the north. This glacier has been among the largest and most stable in Prokletije, due to its strongly shaded position, and, possibly, the great contribution from windblown snow from the plateau. It has a triangular shape and minimum observed area about 2 ha. Series of partially developed moraine ridges surrounds it. In years of appropriate conditions, it freely expands to the north, growing to almost 4 ha. Another moraine marks the usual position of the front. Moraines at this glacier are not big, probably due to the solid rock walls that surround it, which are almost lacking wide couloirs. Three smaller features, possibly snow patches, are situated in the other cirques: to the west Malka Kolata snow patch, a remnant of

**Figure 8.** Small glaciers and snow patches in Kolata range.

a small glacier in the past but now looking shallow with no signs of activity; and two smaller patches to the east of the glacieret.

#### *3.3.4. Karanfili*

(limestone-marble breccia) that cross the ridge in a transverse direction. The scree behind the glacier produces large amounts of debris, which are piled up at the front as a high crescent shaped moraine. Despite that glacier surface is white and clean even after dry summers which indicates the good condition of the glacier and the active recent motion in it. A complex of three fresh stadial moraines is spread down to 500 m from the glacier, indicating its much larger size in the near past. Still further to the NE is the Brjasit small glacier (front at 2280–2300 m a. s. l.), an elongated body of firn and ice (2.5–3 ha), surrounded by moraines from three sides.  Further, another firn feature is found in the East. In September 2015, it was all covered by debris. It is obvious that there is buried ice inside, but despite the huge moraine formed behind the front, we accept

At least two more small glaciers exist in this mountain range. One of them, Upper Zhapor glacier, occupies a high hanging cirque at 2300–2350 m a. s. l. near Zhapores peak. The glacier has a triangular shape, dictated by the topography of its bed, and in 2015, its surface was relatively fresh, with cracks in the lower part reaching 6–7 m depth. A short moraine made of huge blocks separates glacier end from the beginning of a steep couloir, which descends down to the valley of Valbona. The other feature, Stamenov glacier, lies in an easterly oriented cirque to the East of Maja Gryk e Hapt. It has an elongated shape, a clearly visible moraine that surrounds it from three sides and a relatively fresh look on all images taken in autumn.

This prominent part of Prokletije mountain system lies to the NE of Bjelić range, and is connected to it through the pass Qafa e Presljopit (2039 m a. s. l.). Rising sharply between the valleys of Valbona (to the S), Cherem (a tributary of Valbona, to the N and E) and Zarunica (tributary of Vruja and Lim rivers, to the NW), it is crossed by the Albanian-Montenegrin border and hosts the highest peaks of all Montenegro: Zla Kolata (2534 m a. s. l.) and Dobra Kolata (2528 m). The top of the range is a flattened plateau of flysch rocks, at the eastern end of which rises the highest point Ravna Kolata (2556 m), entirely in Albania. The plateau ends with almost vertical limestone cliffs from all sides. Western and southern slopes are very steep in all their height, descending almost 2 km down to the surrounding valleys. The northern and eastern slopes have staircase profiles. There are several deep and relatively narrow

Kolata glacieret lies in the deepest cirque with a central position between the three main peaks of this range. The cirque is 200–250 m deep, with vertical walls from three sides, and looks to the north. This glacier has been among the largest and most stable in Prokletije, due to its strongly shaded position, and, possibly, the great contribution from windblown snow from the plateau. It has a triangular shape and minimum observed area about 2 ha. Series of partially developed moraine ridges surrounds it. In years of appropriate conditions, it freely expands to the north, growing to almost 4 ha. Another moraine marks the usual position of the front. Moraines at this glacier are not big, probably due to the solid rock walls that surround it, which are almost lacking wide couloirs. Three smaller features, possibly snow patches, are situated in the other cirques: to the west Malka Kolata snow patch, a remnant of

this feature as a snow patch because of the lack of signs of recent activity.

cirques, carved to the north of the plateau surface (**Figure 8**).

*3.3.3. Kolata range*

90 Glacier Evolution in a Changing World

Karanfili range is the NE continuation of the wide Radohima massif that lies to the West of Popluk and Mt. Jezerce. To the east, Radohima share is framed by the deep Ropojana valley and the northern and western numerous ranges fork toward the valley of Vermosh (a tributary of Lim river in Albanian territory). Karanfili ridge goes narrow and sharp between the valleys of Ropojana and Grebaja, crossing the state border between Albania and Montenegro. It contains a number of peaks higher than 2400 m a. s. l., the highest being Veliki vrh (the Great peak, 2490 m) in Montenegro. At the end of Grebaja valley, which is on the NW side and is shorter, the great Grebaja cirque is formed. The two glaciers in this area are found within this cirque (**Figure 9**).

Ropojanski glacier is situated right on the state border line, to the west of the southern peak of the Karanfil (2460 m), and to the NW of the deep Ropojana pass. The altitude of this glacier is 1910–2000 m a. s. l., which makes it the lowermost on the Balkan Peninsula. It has a heartlike shape, with a 4 m high moraine at its front. Another glacier (Switzerland glacieret) has been found to the SW, under the northern wall of Vukoces peak. Framed by rocks from three sides, this feature has created short moraines only on the eastern side of its front. In 2015 the upper part was scattered by stone blocks protruding from the bottom. Several snow patches surround Mt. Vukoces from west and south (in a deep hanging cirque opened to Ropojana valley), but they all were melted in September 2016.

A number of sustainable snow patches are located further to the NE, in deep and very narrow cirques on the Montenegrin side, Kotao and Krošnja. On the bottom of the deepest cirque Kotao, carved north from the three peaks of the Karanfil (North peak, the Great peak, South

**Figure 9.** Small glaciers and snow patches in Karanfili range.

peak), are the two lowermost summer-lasting snow patches on the Balkans: at altitudes of 1640 m a. s. l. and 1750–1800 m a. s. l.


**7. Prevention**

Preventing exacerbations is an important treatment goal in COPD. There is a wide range of preventive measures which have proven to reduce exacerbation frequency or hospitalization in patients with AECOPD.

#### **7.1. Supportive measures**

Influenza vaccination and pneumococcal vaccination have both been researched as preventive measures for infection associated exacerbations. Current GOLD guidelines [8] advise influenza vaccination for patients with COPD. Pneumococcal vaccination is mainly advised for elderly patients with COPD. Investigation on this subject is ongoing. Of the non-pharmacologic interventions, pulmonary rehabilitation is the most effective in reducing hospital admissions and mortality and improving health-related quality of life in COPD patients who have recently suffered an exacerbation of COPD [74].


Abstract

As the contribution of renewable energy sources is increasing year over year, the effect of harmonics on power system becomes important, and it requires special attention. In conventional power sources, the harmonics is not generated at the source side; only load side is contributing in the harmonics. But renewable energy sources, particularly wind and solar, are based on power electronic devices, so it generates harmonics. This harmonics may have an adverse effect on the system. Harmonic resonance is one of the phenomena, due to which the harmonics are amplified and give rise to several trivial issues. Various methods are used to control the harmonics in the system. Harmonic filter is one of the simple ways to absorb the harmonics generated at load and generation side. Various filter designs have been found in literature as well as in the field. The filters are classified according to their design, construction and operation method. There are two main categories, active filters and passive filters. The passive filters are widely used due to its simplicity and lesser cost. However, to achieve the better performance, it is also used with active filters, and this combination is known as hybrid filter. The response of filters is modified as per the system requirement using various techniques. In this work, the impedance characteristics of various filters are discussed and analysed. Also, how the control structure of power electronic devices affects or modifies the output impedance of converter is also discussed.

Keywords: voltage source converter (VSC), pulse width modulation (PWM), grid-connected converter, filter, harmonic resonance, doubly fed induction generator (DFIG), Nyquist criteria, damped filter


**10. Conclusions**

HS is a chronic disease that causes significant weakness and suffering. Its onset in young adulthood leads to loss of productivity given the limiting nature of the disease. Treatment must be individualized, according to the extent, severity, and degree of interference in quality of life. Topical or oral antibiotic therapy may be effective to treat mild diseases in small areas. Biological agents can be applied to severe or widespread diseases. New treatment options are emerging to target inflammatory agents. Perianal, perineal, and refractory cases of HS should be vigorously treated. Best outcomes are achieved with large resections and reconstructive procedures.


**5. Impact of LVAD implantation on sarcopenia**

As mentioned earlier, many investigators have shown that sarcopenia was associated with increased comorbidity and mortality after implantation of LVAD. On the other hand, only limited studies concerning the impact of LVAD implantation on sarcopenia have been available. Several investigators reported improvement of HGS after implantation of CF-LVAD [21, 22]. Although it has been reported that frailty prior to BTT LVAD implantation is associated with an increased post-LVAD morbidity and mortality, it has also been reported that frailty is reversible in most patients who survive the perioperative period [45, 46]. Maurer et al. [47] assessed reversal of frailty in 29 elderly frail LVAD recipients with a mean age of 71 years. Although frailty improved overall, 53% of the patients remained frail 6 months after LVAD implantation. These data suggested that frailty may be less reversible in aged patients supported with LVAD.

Multiple studies have shown that implantation of LVAD not only provides adequate hemodynamic support but also improves renal and liver function and psychical capacity especially after receiving physical rehabilitation. However, there are multifactorial limitations to exercise in patients supported with LVAD [38]. Although LVAD implantation improves hemodynamics in end-stage HF patients at rest, the device is unable to provide full circulatory support during exercise,

especially in patients with CF-LVAD. Thus, significant limitations in exercise capacity persist soon and long after CF-LVAD implantation. Maximizing LV unloading and improving native myocardial function in association with an automated increase in LVAD speed could provide an increase in maximal exercise capacity in patients with the old-type pulsatile implantable LVAD. However, CF-LVAD can provide only partial improvement in maximal exercise capacity. Further studies are needed regarding the role of RV function, recovery of native cardiac function, the role of rehabilitation and nutrition intervention, changes in skeletal muscle function after CF-LVAD, and their contribution to endurance exercise [38].

## **6. Impact of HTx on sarcopenia**

Fernandes et al. [48] investigated the impact of HTx on the recovery of peripheral and respiratory muscle mass and strength in patients with congestive HF. They showed significant decreases in a cross-sectional area of the bilateral psoas major muscle (CSAbPm), a bilateral HGS, and the maximum inspiratory and expiratory pressure (MIP and MEP) in patients on the waiting list compared with the healthy controls with normal cardiac function. They also found significant increases during waiting for HTx to 6- and 18-month post-HTx in the CSAbPm (1305.4 vs. 1458.1 vs. 1431.3 mm2 , respectively), bilateral HGS (27.3 vs. 30.2 vs. 34.7 kg/f, respectively), MIP (59.5 vs. 85.5 vs. 90.9 cmH2O, respectively), and MEP (79.5 vs. 93.2 vs. 101.8 cmH2O, respectively). These results revealed that patients recovered peripheral and respiratory muscle mass and strength early after HTx. However, Schaufelberger et al. [49] demonstrated that intrinsic abnormalities in skeletal muscle found before HTx remained 6–9 months after HTx and might contribute to a reduced exercise capacity and muscle strength in these patients, in contrast to the former paper's findings.

## **7. Management of sarcopenia after LVAD implantation**

As mentioned earlier, sarcopenia is a strong negative predictor on outcome after LVAD implantation and HTx. Therefore, sarcopenia is one of the main therapeutic targets in patients with end-stage HF referred to LVAD implantation and HTx to avoid related comorbidity and to improve prognosis post-LVAD implantation and post-HTx. Although moderate or severe sarcopenia as well as frailty is a contraindication for HTx, patients who can reverse frail after LVAD implantation would be considered eligible for HTx. Therefore, to further improve outcomes after LVAD implantation or HTx, therapeutic management for sarcopenia should be established in patients supported with LVAD as well as those prior to LVAD implantation. As the management of sarcopenia in patients prior to LVAD implantation might be the same in medically treated patients with end-stage HF and has been previously well discussed in many previous literatures, those for patients supported with CF-LVAD will be discussed in this review.

According to the pathophysiological factors involved in the pathogenesis of sarcopenia, therapeutic approaches for sarcopenia are summarized in **Figure 2**. Although Khawaja et al. [22] reported that CF-LVAD implantation corrects GH/IGF-1 signaling and improves muscle structure and function, only limited data were available regarding anti-inflammation strategies and hormonal therapies, such as GF/IGF-1 and ghrelin administration for sarcopenia in patients supported with LVAD. Therefore, exercise training and nutrition supplementation in patients supported with LVAD are reviewed in this review.

*Sarcopenia in Patients with End-Stage Cardiac Failure Requiring Ventricular Assist Device or… DOI: http://dx.doi.org/10.5772/intechopen.100612*

**Figure 2.** *Sarcopenia pathogenesis and therapeutic approaches: GH growth hormone, IGF-1 insulin-like growth factor-1.*

#### **7.1 Exercise training (rehabilitation) in LVAD patients**

Generally, HTx or LVAD recipients attend a cardiac rehabilitation program to promote recovery after surgery. Such rehabilitation programs consist of standardized sessions of physical exercise training, with the same intensity and duration regardless of HTx or LVAD implantation. However, surgical indication and method, individual medical and surgical therapies, and possible adverse events after surgery might affect the efficacy of cardiac rehabilitation differently in HTx and LVAD patients. If this occurs, rehabilitation programs better tailored to LVAD patients should be designed.

Yanase et al. [44] reported that short term, such as 3-month rehabilitation program, could significantly increase post-HTx exercise capacity irrespective of age, gender, type of LVAD, and underlying disease. But, even in those patients, better several nutrition factors at exercise program admission were significantly associated with peak VO2 at the end of the exercise program. Therefore, nutrition supplementation during LVAD support might be also essential to improve exercise capacity post-HTx as well as exercise training. However, there are no guidelines regarding the best way to cardiac exercise prescription, especially for CF-LVAD patients. As a result, LVAD patients currently undergo rehabilitation protocols designed for other types of cardiovascular diseases or cardiac surgeries.

As patients receiving LVAD are deeply deconditioned due to advanced HF, it is recommended that patients with sarcopenia as well as frailty are admitted to an in-patient rehabilitation program soon after implanting LVAD. Alsara et al. [50] reviewed the literatures regarding cardiac rehabilitation in patients supported with LVAD and concluded that exercise training is safe and recommended early mobilization between 7 and 10 days post-LVAD and treadmill exercise training beginning at 21 days post-LVAD. However, there is very few information regarding the improvements derived from exercise training in LVAD patients.

Currently, pulsatile-flow LVADs (PF-LVADs) are seldom used as durable support in patients with end-stage HF, but they have a pneumatically/electrically driven ventricle operating in the complete fill/ and empty mode. Therefore, cardiac output during exercise will increase by an automatic increase in pump rate responding to an increase in left ventricular (LV) preload. PF-LVADs work independently from LV afterload and produce a maximal cardiac output of 10 liters/min with a pump rate

of 120 beats/min [51]. On the other hand, the CF-LVAD has no inflow or outflow valves, unloads the ventricle in both systole and diastole, and operates at a fixed pump speed. The two types of CF-LVADs are axial and centrifugal. Pump flow changes according to the differential pressure between the inflow and outflow cannulas. The sensitivity of axial and centrifugal pumps to changes in preload is similar, whereas centrifugal pumps are more sensitive to afterload [52]. During exercise, pump flow increases in the CF-LVAD according to changes in LV preload and afterload. For example, RV failure decreases LV preload and high systemic pressure decreases LV afterload, resulting in reduced pump flow. Therefore, CF-LVAD cannot fully increase pump flow with exercise, whereas PF-LVAD can do so.

Haft et al. [53] reported the differences in the exercise hemodynamic responses between PF-LVAD and CF-LVAD. Peak VO2 as well as resting central venous pressure, mean arterial pressure, and pulmonary capillary wedge pressure were similar and pump flow increased peak VO2 in both groups. However, the increase in pump flow was approximately 20% greater in the PF-LVAD than in the CF-LVAD. Moreover, the significance of this finding is unclear because the pump flow through for the CF-LVAD is not directly measured but only estimated. Martina et al. [54] reported that patients supported with CF-LVAD showed a mean peak VO2 of 18 mL/kg/min (55% of predicted) and a mean total maximum cardiac output of 8.5 liters/min. From these studies, patients supported with CF-LVAD may have a similar peak VO2 independently of the type of CF-LVAD. Although maximum cardiac output increases with exercise in patients supported with CF-LVAD, it does not reach levels found in healthy individuals with normal cardiac function.

Many factors, such as underlying heart disease, native heart function, especially right ventricular function, both ventricular morphology, co-existing arrhythmia, type of LVAD, rehabilitation protocol, and nutrition intervention may influence the effect of cardiac rehabilitation on improvement in exercise capacity and recovery from sarcopenia. Therefore, individualized exercise prescriptions leading to optimal improvements in exercise capacity in patients supported with CF-LVAD are not well known and should be established in the field of LVAD therapy [47].

#### **7.2 Nutrition**

There is no doubt that malnutrition is involved in the pathogenesis of sarcopenia, and that it contributes to the poor muscle function observed in patients with end-stage HF, particularly in frail elderly patients. In general, the proposition of nutritional interventions should be based on the delivery of an adequate energy supply and on the supplementation of specific nutrients as an effective treatment in preventing and/or reversing sarcopenia in patients with advanced HF. However, there are very few literatures regarding the recovery from sarcopenia by nutrition interventions particularly in patients supported by LVAD.

### **8. Conclusion**

Sarcopenia as well as frailty is a strong negative predictor on outcome after LVAD implantation and HTx. Assessment of skeletal muscle function such as HGS and gait speed, and measurement of skeletal muscle mass and CER index prior to surgery are useful tools to predict patient's outcome after LVAD implantation and HTx. Therefore, therapeutic strategies to reverse sarcopenia prior to surgery and after LVAD implantation are important to improve their outcomes. However, many factors, such as the indication, surgical method, postoperative therapies, and possible adverse events, might affect the efficacy of cardiac rehabilitation and nutrition *Sarcopenia in Patients with End-Stage Cardiac Failure Requiring Ventricular Assist Device or… DOI: http://dx.doi.org/10.5772/intechopen.100612*

supplementation on quality of life as well as survival differently in HTx and LVAD patients. Therefore, individualized exercise prescriptions and nutrition interventions leading to the reversal of sarcopenia as well as frailty in patients undergoing and supported with CF-LVAD should be established in the near future.


**Meet the editor**

Assistant Professor Ana Polona Mivšek, PhD, is a midwifery teacher at the Faculty of Health Sciences, University of Ljubljana, midwifery department. She finished her BSc in midwifery in Slovenia and her MSc in midwifery in the UK. Her PhD in sociological studies enabled her to have a deeper insight into the current trends of the midwifery profession.

She has worked in the delivery room of the maternity hospital in Ljubljana. Currently, she is lecturing midwifery and sexology in midwifery and teaching practical training to students in connection with physiological and pathological pregnancy.

Besides midwifery she is also interested in combining different knowledge with the aspects of midwifery care, such as psychology, sociology, sexology and ethics. Her primary focus of interest is on preconception health, midwifery care during healthy pregnancy and uncomplicated birth.

Contents

**Preface VII**

**Provision 1**

Masitenyane

**Long Term 37** Ruth Mielke

**Associated Factors 65**

Angwafo and Rosemary Ogu

Chapter 6 **Forensic Midwifery 111** Sevde Aksu

Chapter 1 **Basic Antenatal Care Approach to Antenatal Care Service**

Chapter 2 **Psychosocial Antenatal Care: A Midwifery Context 15**

Chapter 4 **Mistreatment of Women in Health Facilities by Midwives during Childbirth in Ghana: Prevalence and**

John Kuumuori Ganle and Ebenezer Krampah

Chapter 5 **Improving Maternal Health: The Safe Childbirth Checklist as a Tool for Reducing Maternal Mortality and Morbidity 87** Julius Dohbit, Vetty Agala, Pamela Chinwa-Banda, Betty Anane-Fenin, Omosivie Maduka, Ufuoma Edewor, Ibimonye Porbeni, Fru

Johanna Mmabojalwa Mathibe-Neke and Seipati Suzan

Thembelihle Sylvia Patience Ngxongo

Chapter 3 **Pregnancy Weight Gain: The Short Term and the**