*4.1.6 Shoot borer:* Sesamia inferens *walker (Noctuidae)*

All of the southern states of India, including Andhra Pradesh, Karnataka, and Kerala, have primary and secondary nurseries with oil palm seedlings where the shoot borer is present (**Figure 7**).


**5. Conclusions**

temperature and gas composition, may occur via reaction with CaO to form Ca3

diffusing through the gas to the aqueous phase of the sorbent slurry where As2

BO3

BO3

leachable, we can assume that FA containing B species such as CaHBO3

*Selenium* casually present as selenide in coal is volatilised as elemental Se0

2−), selenotrithionate (Se(SO3

of Se can remain in the flue gases and be emitted into the atmosphere.

remain as a monatomic species or may oxidise to Hg2

solve. It is speculated that some of the absorbed Hg (HgCl2

re-emitted, S (IV) being the main precursor of Hg0

FGD systems [52]. However, gaseous Hg0

by which Ca3

hydrated to H3

in the range 90–99%.

main route by which H3

boiler, gaseous SeO2

selenosulphate (SeSO3

elemental Hg (Hg0

of Hg0

As2 O3 AsO4

the sprayers and dissolve to AsO4

AsO4

the chemisorption mechanism of H3

FGD gas-to-liquid contact zone, H3

aluminium silicates. Boron is generally released as H3

138 Air Pollution - Monitoring, Quantification and Removal of Gases and Particles

BO3

increase B content in the in the FGD-gypsum [49].

small fraction of FAs in the flue gas that escapes from the control would be the main route

remains in the gas phase during the post-combustion atmosphere, a proportion of gaseous

could enter the FGD either by reacting with moisture in the flue gas to form H3

and condense in the scrubber as the flue gas undergoes a rapid quench (50–60°C), or by

may differ. Generally, As is mostly partitioned in the FGD-gypsum with values comprised

*Boron* is largely organically associated in coals although a fraction can also be associated to

and HBO2

the sorbent slurry when flue gas passes through the sprayers and remain in the FGD reaction tank. Depending on the operating FGD conditions, B partitioning and fate may differ but in general, B is removed in the aqueous effluent (filtered water) and only a fraction of B may remain in the flue gases. However, since B concentration in FAs is relatively high and largely

main route by which Se would reach the FGD is the small fraction of FAs escapes from the control and reaches the FGD. In such a case, Se chemisorbed in FAs could dissolve in the aqueous phase of the lime slurry to form an array of aqueous Se-complexes such as

by reaction with polyoxysulphur donors [50]. Selenium can either be removed in the aqueous effluent (filtered water) or partitioned in the FGD-gypsum. However, a small fraction

*Mercury* occurs in coals in mineral sulphide impurities, although other forms of occurrence, such as Hg-Se species, have been described [51]. During combustion, Hg is released as

AsO4

3− in the aqueous phase of the sorbent slurry. If As2

and HBO2

may diffuse through the gas to the aqueous phase of

2−) and selenopentathionate (Se(S2

2+ and Hg2+ compounds. The reaction

) can be converted back to Hg0

is insoluble in water and therefore does not dis-

re-emission [53–55].

can reach the FGD is with the incoming FGD flue gas. In the

. Depending on the operating FGD conditions, As partitioning and fate

BO3

can be chemisorbed on the FA surface to form the stable CaSeO3

)2

). During post-combustion, and with decreasing temperature, Hg0

(g) with HCl(g) or Cl2(g) to form HgCl2(g) is generally considered to be the dominant Hg transformation mechanism in coal combustion flue gas [51]. The main route by which gaseous Hg can reach the FGD is with the incoming FGD flue gas. Gaseous compounds of Hg2+ are generally water-soluble and can dissolve in the aqueous phase of the sorbent slurry of wet

AsO4

O3

[48] during PCC. Since

can also contribute to

. In the

O3 )2 2−)

(g) may

and

. The

and SeO2

on FAs has not been documented, the

. The

O3

AsO4

would get

Coal is currently a target to accomplish with the Paris climate agreement for both countries and companies. As a consequence, in 2016, world coal production fell by 6.2%, the largest decline on record. However, coal is the world's most abundant energy resource, meaning that despite the decline in coal production and consumption, coal is and will be a reliable source for power generation. The most negative consequence of coal combustion is the emissions of a number of air pollutants including SO2 , NOx, PM, HCl, HF, Hg and As, Be, Cd, Cr, Pb, Mn, Ni, and Se, integral components of fine PM. A number of studies have shown that FGD chemistry allows also the capture of many pollutants other than S, such as F, As, B, Cl, Se or Hg both in a gaseous form and/or as PM. Most of specialised literature reports that most of trace elements in FGD systems are removed in the aqueous effluent (filtered water) and only a fraction of a few remain in the flue gases (such as B, Hg, and Se). According to these studies, it can be concluded that wet limestone FGD systems reach high retention efficiencies for trace elements (>90%). However, it is also important to note that the retention efficiency of FGD system for trace elements may be reduced because of the emission of fly dust in evaporate droplets saturated with gypsum. In view of the discussion exposed in the review, we can conclude that the emissions of inorganic trace pollutants from coal power generation depend on each facility including the flue gas depuration train as well as the operating conditions associated to it.

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Preface

A wireless mesh network (WMN) is a wireless network with a large number of stationary wireless mesh routers that are connected using wireless communication techniques to form a mesh structure. Some of these routers act as a client wireless access point (such as laptops, PCs, and smart devices) with wireless connection where these routers attach themselves to the mesh network in order to transmit and receive data via the backbone mesh network. One or more routers are connected to the Internet and serve as gateways.

Nowadays, wireless mesh networks is a rapidly growing topic, but it is still largely new. After being used in military applications at the beginning, WMN moved to civil use and is now being used worldwide as both local area networks (LANs) and metropolitan area networks (MANs). Nevertheless, these arrangements are still 'cutting edge' and it is not yet clear what the most permanent applications of mesh will be – particularly as the application moves from early adopters towards widespread uptake.

This book discusses and investigates some issues related to WMNs, starting from a full overview of this system, describing, in depth, some related research and ending with interesting applications and supporting systems.

**II**

**Chapter 10 149**

Fractal and Polar Microstrip Antennas and Arrays for Wireless

*by Paulo Fernandes da Silva Junior, Mauro Sérgio Pinto Silva Filho, Ewaldo Eder de Carvalho Santana, Paulo Henrique da Fonseca Silva, Elder Eldervitch Carneiro de Oliveira, Maciel Alves de Oliveira,*

*Fabrício Ferreira Batista, Alexandre Jean René Serres, Raimundo Carlos Silvério Freire, Almir Souza, Silva Neto, Severino Aires de Araújo Neto and Carlos Augusto de Moraes Cruz*

Communications

**Mutamed Khatib, PhD and Samer Alsadi, PhD** Palestine Technical University - Kadoorie, Tulkarm, Palestine

**1**

**Chapter 1**

**Abstract**

and applications.

**1. Introduction**

**2.1 Architecture**

**2. Wireless mesh network**

Networks

*J. Rejina Parvin*

An Overview of Wireless Mesh

Wireless mesh networks (WMNs) are communication networks which comprise radio nodes in which nodes are arranged in a mesh topology. Mesh topology is an interconnection of all nodes connected with all other nodes in the network. The network includes devices like nodes, clients, routers, gateways, etc. As the nodes are fully connected, mesh networks are usually less mobile as rerouting is less difficult in predicting the reroute results in delay in data transmission. Mesh clients can be of any wireless devices like cell phones, laptops, etc. The gateways which act as forwarding nodes may not be connected with the Internet. As different devices come under a single network, it is also referred as mesh cloud. WMN is self-healable. It works better with various different networks which include cellular networks and IEEE 802.11, 802.15, and 802.16 as well. WMN is flexible to work with more than one protocol. This chapter gives architecture, layer functionalities,

**Keywords:** WMN architecture, layer functionalities, WMN standards, applications

Wireless mesh network is a network which comprises various wireless nodes with access points. Each node in the network acts as a forwarding node to transfer the data. Since the network is decentralized, forwarding of data is possible only to the neighboring node. This results in the network structure simple and easy. WMN makes the people connected with the Internet who work at remote areas and operating business. This chapter throws light on WMN architecture, layer functionalities,

Wireless mesh network is the architecture which provides less mobility with low cost within a radio range. WMN is an infrastructure which is a network of routers minus cabling between the nodes. It consists of radio nodes which need not to be cabled to a wired port like the conventional wireless access points. Shortest hops are predicted to transmit the data toward large distance [1]. Nodes between the source and destination act as a forwarding node which works cooperatively in making decisions in route prediction based on the topology and forwarding the data.

various other networking standards, and applications.