Solutions of some nonlinear parabolic equations with initial blow-up

We study the existence and uniqueness of solutions of $\partial_tu-\Delta u+u^q=0$ ($q>1$) in $\Omega\times (0,\infty)$ where $\Omega\subset\mathbb R^N$ is a domain with a compact boundary, subject to the conditions $u=f\geq 0$ on $\partial\Omega\times (0,\infty)$ and the initial condition $\lim_{t\to 0}u(x,t)=\infty$. By means of Brezis' theory of maximal monotone operators in Hilbert spaces, we construct a minimal solution when $f=0$, whatever is the regularity of the boundary of the domain. When $\partial\Omega$ satisfies the parabolic Wiener criterion and $f$ is continuous, we construct a maximal solution and prove that it is the unique solution which blows-up at $t=0$

Initial trace of solutions of semilinear heat equation with absorption

We study the initial trace problem for positive solutions of semilinear heat equations with strong absorption. We show that in general this initial trace is an outer regular Borel measure. We emphasize in particular the case where $u$ satisfies (E) $\partial_t u-\Delta u+t^\alpha |u|^{q-1}u=0$, with $q>1$ and $\alpha>-1$ and prove that in the subcritical case $

On uniqueness of large solutions of nonlinear parabolic equations in nonsmooth domains

We study the existence and uniqueness of the positive solutions of the problem (P): $\partial_tu-\Delta u+u^q=0$ ($q>1$) in $\Omega\times (0,\infty)$, $u=\infty$ on $\partial\Omega\times (0,\infty)$ and $u(.,0)\in L^1(\Omega)$, when $\Omega$ is a bounded domain in $\mathbb R^N$. We construct a maximal solution, prove that this maximal solution is a large solution whenever $q<N/(N-2)$ and it is unique if $\partial\Omega=\partial\bar\Omega^c$. If $\partial\Omega$ has the local graph property, we prove that there exists at most one solution to problem (P)Comment: 16 page

Cities as emergent models: the morphological logic of Manhattan and Barcelona

This paper is set to unveil several particulars about the logic embedded in the diachronic model of city growth and the rules which govern the emergence of urban spaces. The paper outlines an attempt to detect and define the generative rules of a growing urban structure by means of evaluation techniques. The initial approach in this regards will be to study the evolution of existing urban regions or cities which in our case are Manhattan and Barcelona and investigate the rules and causes of their emergence and growth. The paper will concentrate on the spatial aspect of the generative rules and investigate their behaviour and dimensionality. Several Space Syntax evaluation methods will be implemented to capture the change of spatial configurations within the growing urban structures. In addition, certain spatial elements will be isolated and tested aiming to illustrate their influence on the main spatial structures. Both urban regions were found to be emergent products of a bottom up organic growth mostly distinguished in the vicinities of the first settlements. Despite the imposition of a uniform grid on both cities in later stages of their development these cities managed to deform the regularity in the preplanned grid in an emergent manner to end up with an efficient model embodied in their current spatial arrangement. The paper reveals several consistencies in the spatial morphology of both urban regions and provides explanation of these regularities in an approach to extract the underlying rules which contributed to the growth optimization process

Crude oil and refinery streams desulphurization using slurry dispersed catalysts and ionic liquids

Petroleum refining is among the most important industries in the world. The oil refinery products contribute in many essential issues in the human life including transportation fuels, heating fuels, petrochemical industries, etc. Although oil refining is an old process started in the mid of the 19th century, new developments and technologies are introduced frequently due to the large amount of studies conducted around the world research centres. Some of the petroleum refining processes gain more attention in terms of research and development in the last couple of decades. For example, the importance of developing the hydrocracking process is increasing due to the increasing amount of heavy unconventional oil reserves. Another hot topic is the development of the hydrodesulphurization process due to the environmental concern about the sulphur oxides emissions produced by using oil refinery streams that contain several organic sulphur compounds. In this work, commercially available slurry catalyst precursors are tested to study the impact of the catalyst preparation conditions on its characteristic and activity. Those types of catalysts are used for hydrocracking and upgrading processes of heavy crude and residue including sulphur and other metal removal. The main subject was to approach the desulphurization activity and selectivity of the catalyst in removing dibenzothiophene (DBT) from model feed. DBT is one of the refractory sulphur compounds in the heavy oil fractions. It was found that changing the preparation conditions in terms of temperature, pressure and sulphiding agent influenced the activity and selectivity of the produced catalyst between the direct desulphurization reaction pathway and hydrogenation reaction pathway in removing DBT. The highest conversion was achieved by using cobalt-molybdenum-sulphide catalyst (Co-Mo-S) where up to 94.0 wt% of the DBT was converted. Adding the same catalyst precursor directly to Arab heavy crude oil, high desulphurization level was achieved where 70 wt% of the sulphur content of the feed has been removed. In addition, there is a high potential to increase this desulphurization level in treating heavy crude by applying the optimum operation conditions used in presulphiding the catalyst precursor. Ionic liquids (ILs) were also employed for sulphur removal from refinery streams by liquid-liquid extraction process. The ILs are organic salts with low melting points, mostly at room temperatures. Although the sulphur extraction level was very low comparing with the conventional hydrotreating process, this process has the advantage of minimizing the operation costs by reducing the reaction severity in terms of temperature and hydrogen consumption. Around 80 wt% of DBT was removed from model compound using one of the tested ILs. The nitrogen removal was also very high where almost 99 wt% of pyridine was removed from the model oil. However, the sulphur extraction level decreased in treating diesel fuel due to several factors such as the aromatic contents of the feed and the existence of several sulphur and metal compounds. To overcome this problem, the extraction process was repeated several times using fresh batches of ILs. This point has driven the importance of developing an efficient regeneration method for the used IL which was also approached in this work

Virtual Communities and Patterns of Social Interactions in ‘Tech City’

The impact of social media and Web 2.0 on socioeconomic behaviour in the physical space of the built environment had recently become a matter of intense debate in social sciences and human geography. This paper examines the relationship between the configurations of urban space from the perspective of 'space syntax' theory by Hillier and Hanson (1984) and the configurations of social networks in Twitter, whilst focusing on the technology start-up cluster in 'Tech City' London. Where there has been arguments made for a strong correlation between twitter ties in businesses and physical distance, this research is focused on the borough scale aiming to outline a relationship between the configurations of streets and the virtual and socioeconomic attributes of start-up businesses. The paper reports a moderate relationship between indices of centrality in twitter network and its correspondent measure in street networks. In addition, the research yields global and temporal patterns of relationships with land uses and land values. The paper concludes by reflecting on how the configurations of twitter Tech-City community are present in the physical medium, where short and long links define the local and global part-whole relationship between Tech-City and other communities

IDENTIFYNG VALUE –BASED ORGANIZATIONS

Owing to the day-by-day development of technology, global communication, and information networks, the dynamicity of investment and work forces has increased and the organizations such as join stock companies have no choice but to a new organizing era. Value-based organizations are one of the newest forms of today's organizations in which customers are as affecting the production and providing services, working and process strategies, and developing knowledge and competitive power, alongside with the members. "The organizations are always looking for the new methods and creating innovation, and they even name the value of the customer as their 'future source of competitive advantage'" (Kandampully & Khahn, 2004, p.398). Management based on value and value-based organizations are now affecting today's organizations, and values are regarded to be an undeniable source of competitive advantage. Hence, effectively managing the relationship with the customer, and creating and presenting values are the main mission of such organizations. This paper is attempting to provide a definition for the concept of value, and discuss the nature, their features and aspects, the importance, the advantages, key factors in their success, the phases of creating a value-based organization, expanding the values, the future of such organizations, their challenges, and also the role of the leaders in institutionalizing the valuesValue, Value-based Organizations, Value-based Management

ABC Diffusion in the Age of Digital Economy: the UK Experience

Since the beginning of the 21st century, there has been a call for further research to trace the effects of the speedy changes in business environment on management accounting practices. This study assesses the impact of different information technologies on ABC adoption and implementation. It uses a cross-sectional survey of financial directors and controllers in the UK firms. Postal and electronic questionnaires have been used in order to collect the empirical data. The findings revealed that the rate of ABC adoption has shown a number of changes between 1999 and 2005. The proportions of ABC users and those currently assessing it have dramatically fallen. The percentage of firms rejecting ABC has slightly fallen as well. However, there has been a considerable increase in the number of firms that abandoned ABC implementation and those firms that gave no consideration for its implementation. These results indicate a decrease in the popularity of ABC. ERP systems seem to have a slightly low significant impact on the initial decision of ABC adoption in those firms that do not have any consideration for ABC and firms that have an ERP system before ABC adoption. Furthermore, the results indicate that firms use different information technologies in the ABC assessment and implementation. For ABC assessment, general software applications are the most preferable software packages while a mix of different ABC software packages is the most popular in the case of ABC implementation. Finally, the findings of this study provide an indication on the nature of the possible effect of general IT-related problems on ABC implementation

KAJI EKSPERIMENTAL PENAMBAHAN WIND CUP PADA TURBIN VENTILATOR UNTUK KENYAMANAN RUANGAN

A B S T R A KPenelitian ini membahas tentang penambahan wind cup pada turbin ventilator. Dari kejadian yang sering terjadi di dalam masyarakat, kemampuan mensirkulasikan udara yang masih sangat kurang efisien terutama pada ruangan yang berukuran besar. Turbin ventilator merupakan turbin angin dengan sumbu vertikal yang memiliki gabungan fungsi dari turbin angin dan kipas hisap. Pada penelitian ini di lakukan modifikasi dengan menambahkan wind cup pada turbin ventilator. Tujuan penelitian ini ialah untuk mengetahui pengaruh penambahan wind cup pada turbin ventilator . Turbin Ventilator yang digunakan adalah tipe v30 dan wind cup dengan diameter cup sebesar 7.7 cm. Penelitian ini dilakukan dengan menggunakan ruang (model) uji berbentuk limas segienam yang pada bagian atasnya terpotong untuk meletakkan Turbin Ventilator dan memiliki volume sebesar 0,83 m3. Hasil penelitian menunjukkan penurunan suhu ruangan pada ruang (model) uji adalah sebesar 1-2oc dengan kecepatan angin yang konstan selama 10 menit. Semakin kencang angin yang berhembus maka semakin kencang pula putaran turbin ventilator yang dihasilkan. Daya yang dihasilkan dari putaran turbin ventilator dengan kecepatan angin maksimum adalah sebesar 1,3 watt jika tidak memakai wind cup sedangkan dengan memakai wind cup adalah sebesar 2,21 watt dan peningkatan efisiensi dari putaran turbin ventilator pada kecepatan minimum adalah sebesar 11 %, sedangkan pada kecepatan maksimum adalah 18,1 %